Failed to add Reporting Services to an existing SQL Server Clustered Instance

I have installed SQL Server 2016 Evaluation mode in cluster mode, i had a request to install SQL Server Reporting Services (SSRS) on 
the existing SQL Server clusters.

While i trying to install there is an ERROR there is an error occoured during Feature Configuration 


(

Rule "Existing clustered or cluster-prepared instance failed" 


The instance selected for installation is already installed and clustered on computer xxx. To continue, select a different instance to cluster.

)




Hoping someone here may have a suggestion.

Thanks