Run-time error on setting textbox

I am trying to set a value to a textbox on a subform from a selection in a
popup form. The textbox is bound to a table field (which is a foreign key
/ number field). The listbox on the popup returns a number. When I do:

Forms!frmMainform!frmSubform.Form!txtNumber = Me.lstbox

I get the following error:

Run-time error 2448
You can't assign a value to this object

I have another very similar form where I am able to set a value into a bound
textbox. Why, then, can't I do it on this form? Is there some property
that is set wrong or something? I need to be able to set this value in the
table.

Robert

I think I found the problem, still checking. If it's anything that would be
of interest to anybody, I'll post back here. Thanks.

"Robert" wrote in message
. ..
I am trying to set a value to a textbox on a subform from a selection in a
popup form. The textbox is bound to a table field (which is a foreign key
/ number field). The listbox on the popup returns a number. When I do:

Forms!frmMainform!frmSubform.Form!txtNumber = Me.lstbox

I get the following error:

Run-time error 2448
You can't assign a value to this object

I have another very similar form where I am able to set a value into a
bound textbox. Why, then, can't I do it on this form? Is there some
property that is set wrong or something? I need to be able to set this
value in the table.

Robert