Unable to upload file for converting to MP4

I have tried several versions of the Lame FFP for the library file so I can convert my audio file into MP4 but I get an error message. I have updated to the latest version of Audacity. Please help! window 7 version of audacity is 2.3.1 Thank you!

LAME is for creating MP3 files, and has nothing to do with MP4.
Why do you need MP4?

If you just want to convert files without editing, try [u]TAudioConverter[/u]. Once you’ve configured your output format & destination, it’s just drag, drop, and click, and you can convert a batch of files at once.