i have tried to send 0.0075 eth for matching... gas limit 42000 and gas price 8 gwei set.... but transaction cancellation showed with bad instructions. why???
Did you send it from a contract-type (as opposed to raw) wallet? Smart contracts are restricted from interacting with this contract. It
looks like a large number of your other tx have also failed, so maybe that is the case?
If not, you could try again with a larger gas limit (perhaps whatever your wallet recommends?). MEW recommends 64350, for example (although it only used 41571 last time...).