Your code is assuming that the buffer row is already selected as
required, and this is not necessarily correct. What you need is...

> with DetailQ do begin

BufferRowNum := DataRow[ARow];

> if AColor = clHighLight then begin

which forces DetailQ.BufferRowNum to match the specified grid row.
See DataRow and GridRow properties in the online help for IB_Grid.

hth

--
Geoff Worboys - TeamIBO
Telesis Computing