[TYPO3] Problem Uploading Extension

[Lee M. Childress]

I am using version 4.2.1 of Typo3 and am trying to upload the mm_forum extension. When I do the import, I get the following error:
 
No file uploaded! Probably the file was too large for PHPs internal limit for uploadable files.
 
PHP is configured to allow 12M uploads so size is really not an issue.
 
Has anyone else encountered this error and if so, what was the work-around? I have Googled the problem and see that several have had similar issues, but never read of a "fix".
 
Thanks.