Quote Originally Posted by Russian
Lynn, it's easier than you might think. "Неправильно" - is an adverb, which answers the question как? = Do I do it correctly (Я делаю это правильно?). Нет, я делаю это (как?) неправильно.

(Ваша подпись) неправильна - is a short adjective of неправильная. (answers the question какая? - неправильная), just drop out -я. "Your signature is incorrect." ="Ваша подпись неправильна(-я)".
This does help. I think I need to be more sparing with my use of adverbs in general. Thank you!