if your attempt is successful it is no longer an attempt, it is a done deal. if someone says that they ATTEMPTED something it means they FAILED. otherwise they would say they "DID" it.
put it another way, attempt is an indeterminate quantum state, which upon observation, collapses to either success or failure. at that point, there is no attempt left.
however, your attempt can be up to 99.999999999999999etc. % successful, and still be a failure. only 100% success is true success. or you can redefine your goal to make your failure successful. for instance, the White House did this when its invasion of Afghanistan failed to kill Osama.