$ is undefined - Jquery not found (but included in form)

Hey guys,

I am pretty familiar with Dynamics CRM (except the Online Version). I developed some small plugin which is called from Javascript. Not rocket science, I know. I deployed the solution with all ressources to the MS CRM Online and after opening a marketing list and calling my Plugin (which worked perfectly) I got the following error message: ReferenceError: $ is not defined. After checking my form, I saw that I DID include the jQuery lib as the first script in the form:

So, I have no clue why CRM is telling me that $ is undefined. 

I hope one of you guys can help me with this issue.

Thanks