I don't know how to fix that, but I can suggest how to work around it ...
Turn off the text box's Numbers Only attribute, and instead run a fast clock that check's the last digit entered against "0123456789,"
and chops off the end if it's not acceptable.
The keyboard doesn't look numeric, though.
Alternatively, you could pop up your own arrangements of buttons to act as a numeric keyboard,
with buttons for 0-9, comma, clear, and Done, and a label to show the number in progress.
ABG