'TOO_SMALL_GENDER' => 'Your Gender is TOO Small ...Please Check it!!!.',
Depending on how you modified your code to make it a forced field on registration the above will probably work.
If not ...then replace it with ONE of these below:
'TOO_SHORT_GENDER' => 'Your Gender is TOO Short ...Please Check it!!!.',
'TOO_LONG_GENDER' => 'Your Gender is TOO Long ...Please Check it!!!.',
'TOO_LARGE_GENDER' => 'Your Gender is TOO Large ...Please Check it!!!.',
One of these will work, you have to add it to the bottom of the common.php of your language directory (with the other gender translation lines)...My bet is that the first one is good for you!!
But in fact they all work and they all have a different function
Goodluck The Crow,
...Joshua203
PS ...ofcourse you can change the translation text