You can compound level 36 weapon or equipment as long as you are level 36 or higher. It is a law of compound: you can't compound item which has a higher level than your own level.

You just need a luck and I can understand you will always be frustrated by a lot failures. But failures are a proof that your alchemy level is too low. Another law of compound: How higher the alchemy level, how less failures.

So, I advice you to compound a lot and try every time again, until you have the one what you want. It is like playing the slot machine.