I have the following code that fill a grid. The problem I have is with the line .Column3.wscombobox1.controlsource = ...
Err.mess.:Parent object will not allow this property setting for ffecost.wsgrid1.column3.wscombobox1.ControlSource.

WITH THISFORM.Wsgrid1
.RecordSource = "cur_ffecost"
.Column1.ControlSource = "cur_ffecost.invcode"
.Column2.ControlSource = "cur_ffecost.ecost_mnt"
.Column3.ControlSource = "cur_ffecost.ecost_mnt_cur"
.Column3.wscombobox1.ControlSource = "cur_ffecost.ecost_mnt_cur"
.Column4.ControlSource = "cur_ffecost.vendorcode"
.Column5.ControlSource = "cur_ffecost.vendorname"
.Column6.ControlSource = "cur_ffecost.ref"
ENDWITH

The same control, out of the grid, works perfectly:
THISFORM.wscombobox1.ControlSource = "cur_ffecost.ecost_mnt_cur"

I cannot figure out what is happening here ?

Thanks for any help
Eric