i am not able to backup my phone so i can activate my new iphone. i have storage available so why is this happening?

You do not indicate why it is that you cannot backup your phone, so answering your question is impossible. The ability to activate a new phone is not predicated on the ability to backup the old phone. You can activate a phone without a backup of an old phone, you just could not restore the new phone to the backup of the old phone. See this and then try rephrasing your question and come back. Writing an effective Apple Support Communities question

See this support document for troubleshooting steps. If iCloud Backup couldn’t be completed or you can’t restore - Apple Support

What happens when you try?

Error message? What does it say?

Any info about the issue?