Group by sql lite [android]

Mobile
#1

Ola pessoal tenho a seguinte base.

CREATE TABLE dataRegistry (_id INTEGER PRIMARY KEY,month TEXT, category TEXT, description TEXT,value INTEGER, dateCost DATE,typeCost TEXT);
insert into dataRegistry values (1,‘janeiro’,‘category’,‘description’,2,2012-01-01,‘positive’);
insert into dataRegistry values (3,‘janeiro’,‘category’,‘description’,2,‘2013-01-12’,‘positive’);
insert into dataRegistry values (5,‘xxx’,‘category’,‘description’,2,‘2013-02-12’,‘positive’);

funciona retorna tudo
select * from dataRegistry;

funciona ok retorna tudo do mes 2
SELECT * FROM dataRegistry where strftime(’%m/%Y’,dateCost) =‘02/2013’;

Trava o banco tenho que dar ctrl-C nao entendo por que esse group by nao funciona no sql lite e no mysql sim?
SELECT dateCost FROM dataRegistry group by strftime(’%m/%Y’,dateCost)’;

se alguem puder ajudar agradeço.

#2