TIB_lookupcombo in grid problem

Iam setting up a TIB_lookupcombo in TIB_grid. I have been doing it
again and again for almost the whole day. I have been following every
steps carefully, yet Iam still not getting the right results ....

In a form I have parenttable and lookuptable ... I presented the
parenttable in two ways, one in grid and the other using TIB_edit...
My standalone TIB_lookupcombo works fine while the embedded
lookupcombo doesnot appear to be correct ...

In the grid I have the parenttable.key column and the
parenttable.keydesc column .... The TIB_lookupcombo on does appear if
and only if the grid is in focus and it focuses on the key column,
and in the keydesc column no TIB_lookupcombo appear there ... What am
I missing?

I have check throughly that I have followed every carefully and
correctly