Paypal live and test function not working

Hello, I have tried to use both the “live” and “test” paypal payment but it’s not working. When I entered my paypal test credentials and try to make a test payment I am given an error message. Then when I go to test the “live” paypal payment with the live credentials, I am able to go through the whole thing but the progress bar for the project does not indicate that a money have been add. Your help is greatly appreciated.