You should still be able to restore even if you compressed the backup image. When DB2 does a compressed backup, it stores the compression library into the image. When you restore, DB2 will see that the image is compressed and try to use the library in the image. Unfortunately when you backup on 64 bit, you get a 64 bit library in the image and when you backup on 32 bit you get a 32 bit library. You can see where this will lead to problems when restoring to a different bitness. Luckily, DB2 provides a solution by using the COMPRLIB clause on the restore command. Just supply the library name of the version on the server where you are restoring to and it should work.
Andy