iReport + Hibernate, só executa uma vez o Preview

Boa noite pessoal estou trabalhando com iReport + Hibernate, clico no botão RUN REPORT USING A CONNECTION e ele funciona perfeitamente pela primeira vez, caso eu tente executar novamente recebo a seguinte mensagem:

Filling report... 
  Locale: português (Brasil)
Error filling print... 
Hibernate session opened Hibernate: select pedidoitem0_.CODIGO_PEDIDO as CODIGO1_, pedidoitem0_.CODIGO_PRODUTO as CODIGO2_, pedidoitem0_.QUANTIDADE as QUANTIDADE10_, pedidoitem0_.PRECO_UNITARIO as PRECO4_10_ from TB_PEDIDO_ITENS pedidoitem0_ Hibernate session closed java.lang.ClassCastException: br.com.fts.exp.bean.Produto$$EnhancerByCGLIB$$c49991a0     at ExportaFacilItem_1144880421768_893506.evaluate(ExportaFacilItem_1144880421768_893506:169)     at net.sf.jasperreports.engine.fill.JREvaluator.evaluate(JREvaluator.java:170)     at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:556)     at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:524)     at net.sf.jasperreports.engine.fill.JRFillElement.evaluateExpression(JRFillElement.java:952)     at net.sf.jasperreports.engine.fill.JRFillTextField.evaluateText(JRFillTextField.java:337)     at net.sf.jasperreports.engine.fill.JRFillTextField.evaluate(JRFillTextField.java:324)     at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:275)     at net.sf.jasperreports.engine.fill.JRFillBand.evaluate(JRFillBand.java:399)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(JRVerticalFiller.java:1300)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(JRVerticalFiller.java:631)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:228)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:128)     at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:730)     at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:123)     at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:420)     at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:256)     at it.businesslogic.ireport.IReportCompiler.run(IReportCompiler.java:701)     at java.lang.Thread.run(Unknown Source)  NESTED BY : java.lang.ClassCastException: br.com.fts.exp.bean.Produto$$EnhancerByCGLIB$$c49991a0     at ExportaFacilItem_1144880421768_893506.evaluate(ExportaFacilItem_1144880421768_893506:169)     at net.sf.jasperreports.engine.fill.JREvaluator.evaluate(JREvaluator.java:170)     at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:556)     at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:524)     at net.sf.jasperreports.engine.fill.JRFillElement.evaluateExpression(JRFillElement.java:952)     at net.sf.jasperreports.engine.fill.JRFillTextField.evaluateText(JRFillTextField.java:337)     at net.sf.jasperreports.engine.fill.JRFillTextField.evaluate(JRFillTextField.java:324)     at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:275)     at net.sf.jasperreports.engine.fill.JRFillBand.evaluate(JRFillBand.java:399)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(JRVerticalFiller.java:1300)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(JRVerticalFiller.java:631)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:228)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:128)     at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:730)     at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:123)     at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:420)     at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:256)     at it.businesslogic.ireport.IReportCompiler.run(IReportCompiler.java:701)     at java.lang.Thread.run(Unknown Source)  NESTED BY : net.sf.jasperreports.engine.fill.JRExpressionEvalException: Error evaluating expression :      Source text : ((br.com.fts.exp.bean.Produto)$F{produto}).getDescricaoCompleta()     at net.sf.jasperreports.engine.fill.JREvaluator.evaluate(JREvaluator.java:181)     at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:556)     at net.sf.jasperreports.engine.fill.JRCalculator.evaluate(JRCalculator.java:524)     at net.sf.jasperreports.engine.fill.JRFillElement.evaluateExpression(JRFillElement.java:952)     at net.sf.jasperreports.engine.fill.JRFillTextField.evaluateText(JRFillTextField.java:337)     at net.sf.jasperreports.engine.fill.JRFillTextField.evaluate(JRFillTextField.java:324)     at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:275)     at net.sf.jasperreports.engine.fill.JRFillBand.evaluate(JRFillBand.java:399)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(JRVerticalFiller.java:1300)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(JRVerticalFiller.java:631)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:228)     at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:128)     at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:730)     at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:123)     at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:420)     at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:256)     at it.businesslogic.ireport.IReportCompiler.run(IReportCompiler.java:701)     at java.lang.Thread.run(Unknown Source) Caused by: java.lang.ClassCastException: br.com.fts.exp.bean.Produto$$EnhancerByCGLIB$$c49991a0     at ExportaFacilItem_1144880421768_893506.evaluate(ExportaFacilItem_1144880421768_893506:169)     at net.sf.jasperreports.engine.fill.JREvaluator.evaluate(JREvaluator.java:170)     ... 17 more 
Print not filled. Try to use an EmptyDataSource...! 

Alguém sabe me falar o que deve estar acontecendo ?