It could all just be an input validation error on SAS's website if your KTN really starts with TT or uses a non-standard format. I've had colleagues get hit by this in the past where the composition of their passport number (but which actually had letters and other characters) wouldn't be accepted by the SAS website but was perfectly valid. I guess you're just one of few that runs into this with SAS. I would ask the chat agent to raise an IT issue to have it permanently resolved.