I can't get the tab indexing to work correctly on a user form.

I have a user form with two frames.
the first frame has two combo boxes and a text box, and three labels.
The labels are not indexed, and their tabstop property is set to False.
The other controls tab indexes are set to 0, 1 and 2 respectively.
the first combobox in this frame has focus set when the form is loaded.

the second frame has three text boxes and three labels.
Again, the labels tabstop property is set to False, and the textboxes tab
indexes are set to 0, 1, and 2.

When I tab through, I have to hit the tab key 3 extra times before the
cursor will move from the last text box in the first frame to the first
textbox in the second frame. I'm not sure where those three "tabs" are going
to, as the blinking cursor dissappears until it shows again in the textbox on
the second frame.

How can I make the tab go from the last text box in the first frame directly
to the first textbox in the second frame?