I don't know what's the purpose of the assign in the value of the textbox (I suposse that it is in your textbox class), but I think that there is a conflict with the ControlSource.

Does the error fire when you change the value interactively or programatically?

>I have TextBox on a form, which has a Value_assign method. The ControlSource of the TextBox is bount to a field in a table with the same data type. The contents of the Value_Assign method looks like this:
>
>LPARAMETERS tpnValue
>this.value = tpnValue
>
>When the form is initiated, an error message "Record is in use by another user" is issued on the screen. I know the table that has a field bount to the TextBox is not locked by any other form or program. The form's datasession is set to private and the table is opened as shared (not exclusive). When I suspend the program from the error message into the Debug window, the arrow shows me that the error occured when the second line in Value_Assign above is being excuted.