Unable to finish Gnome engeniering quest

Hello,

I wanted to lear gnome-engeniering. So i went to UC and started the quest then i went to they bay in the Eastern Kingdoms to finish it. After i clicked on complete, the book (Quest item) disappeared and i havent learend gnome-engeniering.

When i tried to do the quest from the beginning it wasnt possible (I think because the game thinks i did it already). So i went to the book where you can change your specifications. Didnt work.

I tried everything. Please help me!

Thanks in advance :)