Resolving API Key Error with External Providers in Clay

Hey guys. I am using a waterfall model to get work email's using already provided Email Finding Providers. I need to add few other's externally but I am having an issue. I am using "get" method for the external provider and it is giving me Api key error. It says "Clay received a undefined error from the API with Content: Header name must be a valid HTTP token ["API KEY"]" How to solve this issue and add the external provider through Clay http request. Thanks.