data type for new query item shows none in Query studio

[swarupa]

Hi Everyone,

I have query regarding Group on Query item in Query Studio..Let me describe the problem briefly...

I have a field called 'Name' in FM. I created a new query item called 'Category' with expression below...
Case 'Name'
when 'White' then 'A'
else 'B'
end

For the new QI 'Category' i set attribute property.. But FM not allowing me to set data type, precision and size properties ....(as per Name field i am trying set these properties to Category field as well).

When i try to apply group on QI 'Category' it showing me the error....'you can not complete this operation because it is not supported by the selected report item . select another command or item and try again'
and data type property showing none in QS.
Where as i am able to apply group by in Report STudio and it works good.
But customer wants the same in QS and it not working..

Can anyone please help me in solving this query...

Thanks in-advance!