animation not working

in blender 2.44, i cannot play an animation. when i click animate, it works fine, but when i click play, it just goes blank. does anyone know why it does this or how to fix it?

racingfan421,

What codec are you using? If I recall, Blender cannot display all of the codecs that can be used for output - xvid being one of them.

what is the codec, and where do i find it?