McCain seems to miss candidate filing in TX: serious?

According to presidential candidate Bob Barr’s site In Texas the Evidence is Clear the Democrats and Republicans both missed the fall candidate filing deadline of August 26.

I know that candidates miss this now and then and still get on the ballot. It happened to GWB in various states in 2004, again because of the late ballot.

So can someone inform us how candidates miss the filing deadline and still get onto the ballot?