Aren't you supposed to run md5sum on the iso? It will then output a long string, you then match the string against the contents of the checksum text file that came with the iso.
For example, recently i downloaded FreeBSD..
$ md5sum 5.4-RELEASE-I386-disc1.iso
Now check it against the CHECKSUM.MD5 file here..
Then again, maybe you are trying to do something i haven't done before, in which case my advice will be no use...lol.