my iPad Air 2 used to text to all apple products and now I can only text to iPods and iPads that use email. I looked at what everyone else did but it didn't help. I get the red error when ever I do try. Please help!
It sounds like the iPad is having difficulty associating numbers with the Apple IDs associated with the people you're contacting. Back up everything via iCloud or by connecting to iTunes and then restore your iPad https://support.apple.com/en-gb/HT201252
Restore information from your iCloud and iTunes backup and make sure that iMessage is activated in the settings of your iPad and try to send your messages again.
If it's still not working then restore the iPad again but set it up brand new.