Export as.jpg filters not showing

can someone tell why when sometimes i export my flash file as a .jpg it doesn’t always export it with certain blur, drop shadow filters etc…

i exported once as 800px x 800px and the filters showed up ok, then i exported the same file, execpt i increased it’s size to 1280px x 1024px and scaled the content accordingly to create as desktop image, exported again and none of the above mentioned filters showed!?!

Am i doing something wrong?

Matt