When an offer is created in HasOffers, you're asked to create either a Pixel Based Offer (iFrame/Image) or a Postback Based Offer (Postback w/ Transaction_id/Affiliate_id). These two protocols are defined at the offer level and the response from PX or the advertiser needs to match this protocol.
If HasOffers accidentally receives the wrong protocol, they will still register the conversion in your Conversion report but the conversion will be rejected with Wrong tracking protocol error.
To override this error, log in to HasOffers and navigate to Company -> Customize Application -> Tracking, then switch Enforce Conversion Tracking Protocols from Enabled to Disabled. This will allow accepting any type of response from PX.