Are those settings straight from the Property Sheet of in code? If in code you need string delimiters [e.g., quotes or square brackets] around the RecordSource, ControlSource, CurrentControl properties.

Do you have any code in the InteractiveChange of the checkbox. If so, what is it? Check the code in any parent classes as well. When you try to check the box, does it look like it tries to put a checkmark there then immediately remove it? If so, you may have some code in the InteractiveChange that is preventing this change. If you open the debugger and look at the Properties of this control, is it still ReadOnly and Enabled? If not put a break point on those properties when those values change to false.

>Grid:
>

>RecordSource = users
>RecordSourceType = 1 - Alias
>ReadOnly = .F.
>

>
>Column1:
>

>ControlSource = users.sendmsg
>CurrentControl = chkntm1
>ReadOnly = .F.
>Sparse = .F.
>Bound = .T.
>

>
>Column1.Chkntm1:
>

>ControlSource = users.sendmsg
>ReadOnly = .F.
>Enabled = .T.
>