there seems to be some problem with open seek in chess 960.  I accepted the challenge by a player with 1200 rating and yet chess.com told me that my rating of more than 1300 is too low to accept the match.  please explain to me the reason for this.  thanks a lot.

The rating limits aren't based on the challenge-issuing-player's ratings. They're set by the other player. He must have them set higher than your rating.

is that so?  thanks for the information.  greatly appreciate it.

When you're logged in and you look at open seeks for standard chess, the games that your rating is too high or too low to accept are not displayed. Chess960 open seeks that you can't participate in *do* get displayed, however. I think that's why it's so surprising to see the "your rating is too high/low to accept" message.