(I feel appropriate in venting this frustration because I give no context whatsoever.)
If you're typing in Microsoft word, as I suspect most of you are, you are bound to notice a little green squiggly line sometimes underneath your sentences. That typically indicates a sentence fragment. Don't ignore it. The lines are your friends. All you have to do is go back and make sure that you have both a subject and a verb in the sentence. Easy as pie.