not able to authorize resources on azure devops

[mohit-devops-azure]

I am practicing the "Add the deployment stage to the pipeline" exercise as per ESI self learning "https://docs.microsoft.com/en-us/learn/modules/create-release-pipeline/5-deploy-to-appservice".
I have created the service connection and created all the necessary environment for the pipeline to run however I get this error on azure devops portal where the 'azurepipeline' fails with error as given below.

There was a resource authorization issue: "The pipeline is not valid. Job Deploy: Step input azureSubscription references service connection Resource Manager - Tailspin - Space Game which could not be found. The service connection does not exist or has not been authorized for use. For authorization details, refer to https://aka.ms/yamlauthz."

No matter how many times I tried to authorize the resources it wont work.
The app service is created on portal in westus2 region.
I am using the same accounts to login on Azure devops and Azure portal.

[JeanvanHeerden1986]

hmmh