A matching error occurred when MH returned a record where one did not exist. It looks like a tariff 8406 was submitted. MH Returned 8406 with a negative dollar amount, and also returned 8407 with a positive dollar amount. Presumably, 8406 was the wrong code, but they'd already paid out, so they negated it then created an 8407, then re-paid it. The problem is, 8407 was never submitted in the first place, so there was nothing to match to. I'm not sure if they are really supposed to do this, it hasn't has only happened this once as well, so I am marking it a low priority.