251: Post handler of module did not return a PHP list
A module is a program which adds a feature that the Aneamal Translator itself does not provide. A module you use accesses the Aneamal Translator’s form API, but its post handler’s returns a more complex PHP array than the expected simple list.
Solution
Mere users of the module are most probably unable to solve this error. It must be fixed by the module developers. You can contact them to make them aware of the problem.