Applying section 179 carryover

I have a section 179 carryover from my sole proprietorship. What income in future years can it be applied against? Only business profits from the same or other businesses? My business is already showing a loss, but I have oil royalty income every year (a profit) that I'd like to apply the carryover against. After doing so during Easy Step, the Federal review reports the amount as an error that I must correct. Is that because I'm applying it against an inappropriate income source?

 

Anyway, I'm thoroughly confused. I can't find any explanation of what income I can apply a section 179 carryover against.