Well it seems like it can't find the datasource so I guess the first question to ask is: did you defined your datasource in the configuration file (/bootstrap/deploy/yourfile-ds.xml)?
I did, but i had this in my datasource (maybe it helps someone else in the future :-)
<metadata> <type-mapping>mySQL</type-mapping> </metadata> </local-tx-datasource> </datasources>
Removing the <metata> element makes it work!
Thanks for the directions!
Thank you, Edwin! It helps me. :)