Why can't I make a custom invisibility spell?

[GhoulSlayer]

Hi all,

I did all of the mage guild recommendations so I could get into the arcane university. I purchased the Ghostwalk spell which grants invisibility for 60 seconds but I don't have enough magicka to use it. I wanted to make a custom version with a shorter duration so I could use it but when I look at the list of known effects invisibility is not listed. I thought maybe it would fall under another name so I carefully read every effect name and I can't find anything that sounds like invisibility. WTH? My character is currently level 7.

[Veugaroth]

Spell effects are available at spellmaking and enchanting altars only if you have a spell or power with desired effect which you can actually cast. This only includes the mastery in the particular magic school, not if you have enough magicka for it. Ghostwalk for example requires Expert Illusion, so you won't see invisibility effect in the list unless you train it to 75 or get a lower mastery spell like Deathly Visage or Shadow Shape which requires Journeyman Illusion (50). Edited April 27, 2011 by Veugaroth

[GhoulSlayer]

Thanks, I figured it out before your reply, but you confirmed my suspicion. ;)