CheckBox is not working in dwr2.0 like dwr1.2 why?

I have migrated my projects from dwr1.2 to 2.0. But I am facing problems
Suppose I have one check box which id is 'chk1'

So my code is.

DWRUtil.setValue("chk1" ,'Y'); so the html show the checkBox tick but in dwr2.0
When I used dwr.util.setValue("chk1" ,'Y') then it is not working


Why....
Any can explain me???