After adding endpoint alias on IS page, did you go to the consumer provider → binders tab → click on binder → change Port Alias to your endpoint alias on properties right side of designer???
Unless you do this, your credentials or other settings from endpoint alias will not be applied to your consumer during the call.
If above steps are not done, at least you can pass the endpoint alias name as input to your connector service while running it.
#webMethods#Integration-Server-and-ESB