Run an executable jar using groovy

I am trying to open an executable jar file. The file uses some dll files as application extensions.

I am running this right now:

def command = Runtime.getRuntime().exec("cmd /c start C:\\Simulator-0088Poynt-dist\\ProtoBaseSimulator.jar")
command.waitFor()

It opens all other types of files except the jar file. It gives me an error "Cannot open"

I also tried :

"cmd /c java -jar C:\\Simulator-0088Poynt-dist\\ProtoBaseSimulator.jar".execute()

It still does the same thing. Has anybody tried anything else? Or does anybody have a suggestion to what could be causing the error?