What does the error: (WePay) Failure - Reason Code(0004) Undefined risk token header mean?
This means that the users browser could not render a risk token. This is a value that needs to be sent to WePay in order to process a transaction. This is a browser dependent issue, and only affects that user/session.
If this problem continues please Submit aNew Support RequestfromHelp->Supportin your administration Dashboard.