I think that maybe you are managing to perceive into the astral, but you're attracting the wrong spirit(s). It takes a lot of energy, in my experience, to make contact with the correct spirit. I wouldn't trust any spirit that shows up too easily. Question it a lot and don't worry about being a little harsh in threatening it to tell you it's true name. It usually takes a few days, again in my experience, to get a spirit to notice me, and know that I want to evoke it. If you do it too quickly without much preparation (I don't mean so much about the tools, I mean more about meditating or scrying the seal of the spirit for a few days before the evocation at least, and telling it what your requests or questions will be) most likely you'll get some lower-level spirit bugging you, telling you it's the real deal, then making promises it won't keep. That happens to everyone. When you start getting results, then you'll know you succeeded.
Of course, it could all be your imagination creating the visions and voices, but like I said, when you get results (asking for something and then getting it) you know you're doing something right.
Good luck.
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