Trading Mininifty, I am sorry to say, is not a professionals game. Please dont mind. There are huge differences, sometimes upto 2 points between the mini and normal size nifty, and if you are watching normal lot nifty charts, keeping a limit order in the market according to THAT chart, Mini Nifty may do a jig of its own, hit your order, whereas normal Nifty would not.
I used to face this, hence, moved away from Mini nifty.