ClassFormatError when executing Midlet on Cinterion Connect Shield | Thales IoT Developer Community

Hello there,

When I start my midlet on the Cinterion Connect Shield I get the following error:

java.lang.Error: ClassFormatError:  56

 - java.lang.Class.forName(), bci=0

 - com.sun.midp.main.CldcMIDletLoader.newInstance(), bci=1

 - com.sun.midp.midlet.MIDletStateHandler.createMIDlet(), bci=63

 - com.sun.midp.midlet.MIDletStateHandler.createAndRegisterMIDlet(), bci=17

 - com.sun.midp.midlet.MIDletStateHandler.startSuite(), bci=24

 - com.sun.midp.main.AbstractMIDletSuiteLoader.startSuite(), bci=38

 - com.sun.midp.main.CldcMIDletSuiteLoader.startSuite(), bci=5

 - com.sun.midp.main.AbstractMIDletSuiteLoader.runMIDletSuite(), bci=134

 - com.sun.midp.main.AppIsolateMIDletSuiteLoader.main(), bci=26

MIDlet:helloworld.HelloWorld abnormal exit

MIDlet:helloworld.HelloWorld abnormal exit

I am using Netbeans8.1 with the JavaME1.4.1 Plugin and JDK 1.8 for creating my midlet.
Does anyone has an idea  what could be the problem here?

Thanks, 

Nicolas