>>I have two grids in a form that are related via the Data Designer. Simple PO_Header and PO_Detail type stuff. I want to click on a column header in the PO_header grid and have that column sorted, but get the following error: "Command cannot be issued on a table with cursors in table buffering mode".
>>
>>The Form properties are : Buffermode =0
>> and DataSession = 2 (Private)
>>
>>What am I doing wrong?
>
>It seems that you're trying to index a cursor having buffering property =5 (table buffering). It's prohibited and VFP raises the message you really see. Open your DE, and check BufferModeOverride property for the appropriate cursor. Note, that you can index a cursor if you use Buffering=3 (row buffering). It's usually used for views.

Just to add: if you still need table buffering you can switch it to 3 - Row Buffering), index it and switch back to 5 - Table Buffering