We amended some T5s and the CRA won't accept them because they weren't validated using a "validating parser'.  Should the validating parser be already included in the software?  If not, do I need to download additional software?

Here's the exact message:

RE/Objet: Reference ID/No de référence 5557 Our Submission Number EMPU_email Return

We are unable to process your submission because it does not conform to our specifications. We strongly recommend that you validate all submissions with a validating parser before you file. Please validate your file, correct it and then resend your submission.
For further details on filing electronically, please visit canada"dot"ca/taxes-iref. For information or assistance creating an XML file call the Electronic Media Processing Unit at 1-800-665-5164, between 7:00 and 17:00 (EST). If you are outside of Canada, call 613-940-8599.
This is an automatically generated message. Please do not reply to this email as responses are not monitored.