I am having a strange problem with TabIndex in one of my subforms.
It does not change. I change the numbers but nothing happens and the columns order does not change. (Access 2003)
Access has some warped memory of column order for DataSheet view. When I ran into this problem, the only way I was able to resolve the problem was to rebuild the query (copy the string to notepad. then copy it back and paste it into a new query). But start by opening the form in form view and see if you can manipulate the show/hide columns properties. That might also fix it.
This method works for me (A2010)
Click & hold the datasheet column header that you want to move.
Wait until a thick blue vertical line appears down the left of the column (about a second). Drag the column to the new position.
NOTE: You can do this with 2 or more adjacent fields together
Save.
Close.
Reopen and the new datasheet column order has stuck!