TestLink

I am trying to use the great testlinkjavaapi, but I have one problem, I am not capable to create a new testcase programatically
Anyone succeed? The error I get is: (wich should be Error creating test case, it's wrong in the code)
TestLinkAPIException: Error creating test plan: Failed to parse server's response: Expected methodResponse element, got pre
what are the correct parameters? how do I get the internalId? what is the order?
In testlink I see that my testcase is created, but without a number:
If the prefix is XXX, the test is created 'XXX - testlinktest', and clicking on it in the testspecification tab: Your search delivered no results!

I pass null instead of TestImportance.MEDIUM, then it works!
I tried to pass ExecutionType.AUTOMATED, but the testcase is created as manual.

Do you get much help from this forum?
Please reply as I am trying to decide whether to use TestLink and good support is important to me.
Thanks