Grimrock

So, Im pretty certain I understand how the spell system works
You need to know the correct comination of spell runes to toggle, in addition, you have to have spent enough points in that skill tree to unlock whatever skill you are trying to cast.

So for example, you would need 2 points in Fire, to cast the first fire spell, along with the right rune.

Thanks to the web, Ive verified that the spell im trying to cast, is the correct combination of runes.
My mage has a skill of 4 in Ice, which is 1 more than is needed for the level 3 spell, Ice Shards.

Ive got nothing in my hands
Im not wearing any armor (not sure if this matters)
Im not over burdened.
Im not hungry
Ive got full energy (88)

I enter the 2 rune symbols confirmed on multiple website guides, and get the following error:

"you can't use this spells"

My other mage learned fireburst fine, so why on earth is my 2nd mage having issues learning Ice Shards?

Please help

Zewks wrote:"you can't use this spells"

This message is most unusual for LoG. If a spell can be cast there is no message past the "Discovered new spell: <name>" message. If your mage can't cast a spell you will see something like "<name> is not skilled enough to successfully cast this spell". For a wrong rune combo you see the "<name>'s spell fizzles" message and of course if you don't have enough mana you'll see the "out of energy" message.

Are you by chance playing some mod instead of the original Grimrock dungeon, like "Back to the Dungeon" or "Chaos Strikes Back - Remake"? In those mods Ice magic is completely disabled.

EDIT:
found the part where comscript talked about ice magic inside the steam comments:

Mages got ice magic fully maxed because ice isn't available in DM and skills points are at their higher ranks because those points would have been wasted if the player would have increase those skills. And all ice spells are disabled.

I'm using cold damages for the "weaken non-material beings" spells.