>Thank you
>
>But I don't think your solution will solve my problem. If you carefully read my original message again (and try it yourself if you don't mind) you'll see that the problem is NOT how to change/redirect DE (my mistake on thread Title perhaps). The real problem is why changing database (in Load, BeforeOpenTables, or somewhere else) AND specify grid.column.ControlSource to value other than its default will generate an error. If I leave that property unchanged than no error occurs (and I'm sure your trick will work as well).
>
>I will appreciate if you would like to examine the problem once again.

Well, in this case you have to examine tastrade framework
to see what is realy happening in your tastrade form. Apparently some part of functionality is missing that has been provided by tastrade app at run time, since as you said it works fine when you run it from app.
Or tastrade app sets grid properties at run time.

Also see class code for those forms. If I am not mistaken tastrade is little bit 'old' demo app that uses MS foundation classes published with VFP 5.00
It is complex framework all together. Maybe it 'messes up' with grid settings
somewhere in underlying classes.

In general, base grid itself should not 'complain' about it's properties being assigned :))
They get nasty if they loose 'ground' alias at run time.
Also any change of Grid recordsource property (alias) at run time will cause all columns be deprived of it's controlsource property (field) assignments.

What is exactly that you are trying to do with tastrade ?
Are you trying to adapt tastrade in order to make your own app
or you just playing with it?

Help me help you :-))