Shadow, what metal detectors do you have previous experience on? This will help us figure out where to start, to figure out what you may be doing wrong.
There are a lot of nebulous things that printed instructions can never convey, so sometimes, it's better to hook up with someone who's proficient on the particular machine you have, to show actual bench tests on sample targets. Then go to the field, and try comparing flagged targets, etc...
Example: a guy I knew bought at XLT, his first detector ever. He read the instructions cover to cover 2 times. Then went out to an old camp ground to hunt. He noticed that everytime he'd get a signal, it would "disappear". He'd give up, and move on. Then he'd get another signal, and ..... it TOO would disappear! It happened over and over. So he sent the machine back to the factory, for "repair". They sent it back, and he tried again. But the problem persisted! So AGAIN he sent it back to the factory. This time, they called him and said they could find nothing wrong with the unit. The user kept trying to explain the phenomenom, sounds, how he was swinging, etc.... They told him he was using it wrong, and that there was nothing wrong with the machine. By now, my friend was getting very agitated with Whites Co, thinking they were insulting him (like, calling him a dummy or something). He insisted he had read the instructions through 2x and was NOT doing anything wrong.
Eventually, he discovered the problem: Everytime he had heard a signal, he would instinctively "slow down" to "hear it better". Well, being that the XLT is a motion detector (and relatively fast motion, at that), the target would "disappear" the minute he slowed to a crawl to "hear it better". When I asked him later "but didn't you read in the instructions that motion was required?", he said "yeah, but when I read that, I thought that made no sense, because, afterall, how are you supposed to progress through the field, if you are not moving the coil, TO BEGIN WITH?" "I mean, duh, of course 'motion is required', what am I gonna do, stand there and not move around looking for targets?".
So you see, no amount of printed instructions can convey certain things. They simply have to be seen and heard. So too may your question be tied up in something like that. So if you can hook up with any long-time whites user in your area, to go over some bench tests and ground tests, that'd be the best thing.