Godskill Level Stuck/Not Working

Simply put, was godthunder spamming around Apoth and my godskill suddenly stopped working. Opened up my skill tab to find this:

i noticed your out of mp. or did you change class? god thunder needs lancealot

Haha, I figured it out anyways. Was going to delete the topic, but you'd already posted

(yes yes, it was due to mana.. yet the skill still cast so I didn't consider it)