You're Wrong, Now Don't Change

I've been writing reports at my job for almost two years now.

I just received a formal error (a mark that goes against my numbers that are used to determine if I should be promoted or not) for a report that I wrote. I wrote it exactly as I have for the past two years, but this time I was told that I was wrong.

I went to my supervisor and asked him about it. "I got a case returned to me for an error I made. I've been writing reports this way for 2 years. Am I doing it wrong?"

"No," he said, frustratedly rubbing his eyes, "you're doing it the way that I would do it. But it's not worth the fight, so just change it."

"I don't want to fight," I explained, "I just want to make sure I'm doing it right. So, in your opinion, should I change the way in which I'm writing these reports?"

"No," he said. "You're doing it right. It all just depends on who reviews your case. If you get one person reviewing it, they will tell you you're doing it right. Somebody else will charge you the error. Keep doing it the way you were doing it."

Here are the facts:
I was told to write reports a certain way.
I write the reports that way.
I get charged an error for writing them that way.
I am told that I will receive that error for writing reports the way I'm supposed to and I shouldn't change.

This feels monumentally incorrect.

This is, really, my first prolonged experience with working in government/corporate settings. In theatre and film, if you're doing something wrong, you're expected to change until you get it right. Then you're supposed to stay that way. If things change, somebody will let you know, and then you change. So I'm curious: how often does this kind of thing happen and in what contexts does it happen? Because this kind of behavior is, at the least, not healthy: You're wrong, but keep doing what you're doing.