For one report standard filter is not working... why ?

In my customized report, i added from date and to date as dialog field.

And the report is getting filtered according to from date and to date as i did the code in fetch()

But when i added some fields (lets say itemid) in ranges of data sources of the report and selected some item in field “100001” and pressed ok,the report is not getting filtered.

What’s wrong in this ?

I can’t write code for filtering for itemid in fetch() because there is no restriction on selecting more fields then ?

So where i will put this range ?