"[SOLVED] Error: Content is not allowed in prolog"

Hello,

I just started to try to implement RapidMiner into my own application. To make it easier for me I use Jython instead of Java,
which makes the code quite small:

import com.rapidminer.RapidMiner as RapidMiner
import com.rapidminer.Process as Process
import com.rapidminer.RapidMiner.ExecutionMode as ExecutionMode

RapidMiner.setExecutionMode(ExecutionMode.COMMAND_LINE);
RapidMiner.init()
process = Process('D:/RapidMinerRepository/PolynomOptimierung.rmp')
result = process.run()

print result

On running it i get a problem in the Process-line:

Dec 8, 2011 7:56:26 AM com.rapid_i.Launcher ensureRapidMinerHomeSet
...
[Fatal Error] :1:1: Content is not allowed in prolog.
Traceback (most recent call last):
  File "jyRapid.py", line 7, in <module>
    process = Process('D:/RapidMinerRepository/PolynomOptimierung.rmp')
	at com.rapidminer.Process.readProcess(Process.java:1080)
	at com.rapidminer.Process.readProcess(Process.java:1055)
	at com.rapidminer.Process.<init>(Process.java:254)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
	at java.lang.reflect.Constructor.newInstance(Unknown Source)
	at org.python.core.PyReflectedConstructor.constructProxy(PyReflectedConstructor.java:210)

com.rapidminer.tools.XMLException: com.rapidminer.tools.XMLException: Cannot parse document: Content is not allowed in prolog.

The workflow works well in the GUI and in the forum I didn't find any solution, so how to fix it?