I don't understand your question. What, exactly, are you doing? What, exactly, happens? Screenshots help.
Also, some basic information helps. For example:
What version of After Effects? Have you installed the recent updates? What operating system? What kind(s) of source footage? What were you doing when the problem occurred? Has this ever worked before? What other software are you running? Do you have any third-party effects or codecs installed? Tell us about your computer hardware.