kyrolls, it depends on many factors.
How new are you to magic? If you're just starting out, you may just be unfamiliar, or you may need more practice with meditation, energy manipulation, or something else similar.
It could also be the spell. Are you wanting to accomplish something in the actual realm of possibility? If you're trying to grow wings, levitate, or something else similar, it may simply not be possible.
Maybe you're trying something which doesn't need a spell. Some things can be accomplished via divination, meditation exercises, and other methods.