Creating label and the shipment is not working. Failed to authenticate

Hello,

I’m setting up the FedEx Plugin and was able to get the API Keys, meter keys etc for the plugin setup. The FedEx live rates are working, but generating the label and the shipment is not working.

Every time I click to create, it says failed to authenticate. I followed the documentation, to get all the credentials but its still not working Is there something I am missing,