ah, well, there are many reasons, you could have done something wrong in drawing the circle, in the evocations, or in the symbols to summon them, or you arent powerful enough to see, or rip them to where you want them to be. i must ask though...you arent useing the instructions in the little giant encyclopedia of spells and magic...are you...?
sorry? i was refurring to an actual book, not the website, well, i'll take that as a sign that you arent using it, good. if you ever see it in stores, i would honnestly reccomend buying it so it can be burned...its a 'orrible little thing...
well then, what were you useing as the basis to summon the spirit? and for that matter, which spirit?
The most likely reason is that you are attempting magics above your skill level. I know its not so exciting as summoning but perhaps returning to the magic basics to work on proficiency as is recommended for beginners, which according to your own bio is you. Leave the more advanced stuff until you've had some years of experience.
here is the information i have, on a spirit near in name to what you said
Zodiac Position: 20-24 degrees of Pisces
Tarot Card: 10 of Cups
Candle color: Purple
Dantalion is a night Demon and governs 36 legions of spirits
He can produce hallucinations. He reveals the innermost thoughts and desires of, and influences the minds of others without their knowledge.
He knows all human thoughts and can change them at will. He incites love between men and women, and teaches all the arts and sciences. He shows a vision of the likeness of any person.
Dantalian has a blue aura. He usually departs through the ceiling. He can assist in acheiving altered states.
protip, deamons dont like it when you ues "high magic" to call for them, in the interest of your physical and mental health, i'd recommend looking into alternate methods