interac and hosted pay page

I added Interac to my test store.  When I try a transaction it gets declined. I try a second time and it succeeds in that it sends the reponse to the link I have identified for successful transactions.

However, the email I receive says it was declined. The success packet also includes the text "DECLINED RE-TRY* TRANS NOT PERMITTEDCANNOT PROCESS*PLEASE RE-TRY"

Why is it doing this?