Oracle Forms

Hi,
I am trying to filter the number of records shown when i move to form screen by building a dynamic where clause in the when-new-block instance trigger. this is the piece of code

IF ( v_where IS NOT NULL ) THEN

Set_Block_Property('BLOCK_NAME',ONETIME_WHERE,v_where);
go_block('BLOCK_NAME');
Execute_Query(all_records);
END if.

This does not retrieve any records on the screen. But if i comment the set property block and fire it like this
IF ( v_where IS NOT NULL ) THEN

go_block('BLOCK_NAME');
Execute_Query(all_records);
END if

It retrieves all the records for me. I printed out the where clause and checked it. Its passing the correct value and building the right where clause. But for some reason its not retrieving any data when i am trying to filter.