Excelsior

It just doesn't work to cast it that way.

You have to open the spell book.

[cs magicreflect

This spell is also under the in game options macros features. Just scroll down to 'cast spell' option, then go further to the right and single click and hold while pulling cursor downwards, thus scrolling down to the spell 'magic reflection'.

Adrias' way probably works also, but I have not tested it.

Also you can pull the icon of any spell from spellbook and cast from it.