Being Chaptered, is this legal however

First article 15, lying to an nco. I accepted my punishment. During this crazy scheduled 14 day extra duty however another negative counseling came about that recommended another ucmj action. Failure to inform my chain of command about a schedule for extra duty that was approved by my commander for 15 days instead of 14. Was a simple Excel spreadsheet that had his signature on it. First off,is this a legal that could be used as evidence against me when I go to fight this new article 15? Is it even legal for my commander to have approved a set schedule that was not mentioned in my original article 15 that had me pulling 15 days instead of 14?

So because I'm pending a second art15,I'm now facing a 14-12C. I'm trying to push for a chp13 instead as I've failed 3 pt tests in a row because of injuries. Regardless of injuries I've failed the tests.

Opinions?