Stopped (error): X++ Exception:- Language EN-US was not found.

I get the error below when I create a workflow with an email template attached.

Stopped (error): X++ Exception: No message was sent. Language EN-US was not found.

at SysWorkflowWorkItem-create

However,when I set-up the workflow without the email template-it works fine.
NB:- The EMail parameters are set-up fine because the default system notifications via email are working.

Anyone who has experienced this please let me know how you solved it.