Storage/Zip Mobile Error

[Guest kill your phone]

I'm trying to unpack a cab file I emailed myself. When I try, zip mobile tells me "not enough memory to extract the file. delete other files or insert an expansion card". I copied it to the expansion card with tons of room on it. I get the same message. Anybody got a gun?

And why does it say the expansion card? What about the onboard 8GB storage?