Ipad Pro 11 Not Activating Cellular Data Network

[Emdogs39]

Hi, I have an Ipad 11 pro. I signed up for 1gb per month at $20 recurring.  I tried using it recently and it said it "could not activate cellular data network."  I thought I may have gone over my 1gb, so I replenished and added another $20 for another 1gb. It's still not activating. My account is also not showing any data usage recently.  I know the 1gb plan is not being offered anymore but shouldn't it still work?  Thanks for any help.