RNetlogo / NLstart doesn't do anything

Question

I am trying to use Netlogo via R using the following code:

library(RNetLogo)
my.netlogo1 <- "my.netlogo1"

nl.path <- "C:/Program Files/NetLogo 6.1.1/app"
NLStart(nl.path, gui = FALSE,
nl.obj = my.netlogo1, nl.jarname='netlogo-6.1.1.jar')

And I get the following message:

java.lang.NoClassDefFoundError: org/nlogo/workspace/Controllable
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Class.java:416)
Caused by: java.lang.ClassNotFoundException
    at RJavaClassLoader.findClass(RJavaClassLoader.java:383)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    ... 2 more

I heard it was because of a compatibility issue with Netlogo6 but that it had now been solved. Could someone say what I'm doing wrong?