Is there a reason why he shouldn't have to pay child support? Are there any actions I can take to enforce child support benefits for my daughter?

He should put her on his ssi so she would be receiving from that. At least that's the way it works with ssd

Do you have a child support order? If so, he has to pay; it's his problem to figure out how.

And yes, there are things to do to collect it. Are there any other sources of income?

If not, get the court to make him show cause why he shouldn't he held in contempt for failure to pay.
If so, you can also levy those other sources
.