Grievances consistently returned as invalid in Texas

I'm writing to inquire about the "grievance guide." I received this address from the Education-Peer Ed. Instructor. There are times that an inmate or myself find a valid reason to draw up a grievance to bring notice to the matter in question. However the "grievance" department returns the form as "invalid." So is there a specific format or particular details that need to be followed for the grievance to be valid and reach the appropriate authorities, to find a solution?

P.S. I've asked the Law Library Officer and she informed me that such "method" is confidential and not made available to inmates.