Losing rank when win? (chessmaster)

Hi.

I'm a beginner player and am using chessmaster XI GM edition. My question is whether it is possible to lose rate even when I won.

After finishing a game in `Ranked Play' mode, a dialog said I won XX point, but actually I lost rate.

Attached window shows I played with Lucy (I'm black) and won (0-1), but my rating became from 999 to 879. 

Is it possible or a kind of bug?

Thank you in advance.

You should have earned points.It must be another type of time control. 

There's different types of time control: Rapid, blitz, classic, etc.

Yeah, the problem might be due to different time controls. This Ubisoft thread sort of talks about the same problem, although I'm not sure the answer is real clear:

http://forums.ubi.com/showthread.php/509021-Serious-error-in-calculating-rating?s=cb6d82a95aa6b4385b3f6efb190fc3cd

Also, make sure your copy of Chessmaster has the two patches installed, either automatically by the program, or manually by yourself.  Check to see that Chessmaster says it's up to version 1.02. If not, grab the two patches here and install the required patch(es) in order (First 1.01 if needed, then 1.02):

http://forums.ubi.com/showthread.php/341421-Chessmaster-Grandmaster-Edition-Downloads?s=7cea420420db6b3df65df7517acda36f

Guys,

Thank you. It seems it is due to time control. I sometimes change time control. I investigated pgn file and I confirmed I had changed time control when I saw this situation.