Hi @PaulaFarmer970,
Without knowing the details of your Canvas and possible student information system integration, this is going to be very hard for community members here to answer with certainty. My guess is that there is some kind of issue in your student information system that's deactivating the enrollment, possibly in error but also possibly for a good reason. I'd reach out to your enrollment/registration department so they can look into that and possibly resolve whatever the issue there may be.
If that doesn't work out, please let us know and we may be able to offer some other suggestions to try.
-Chris