JNI calls only work if sent from main thread?!?

Hi,
I searched through the forum for a couple of hours now, and found that a lot of developers seem to have problems with JNI and threads. However, I couldn't find a solution to my problem so far...hope you can help!
We need to send requests to a DDE Server from our Java application. For that reason, we implemented a very small DLL using Delphi, which calls the DDE Server and returns the result as a string. Using JNI, we call this DLL from Java.
Everything works fine, as long as we call the DDE Server (via JNI and the DLL) from the main thread of the Java application. But everytime we call it from another Java thread, our DDL reports that it can't get a connection to the DDE Server. This is especially awkward if you want to make calls as a reaction to GUI events, since then the call is sent by the Event Dispatch Thread of the Java runtime.
This does not seem to be a multi-threading problem, since we do never send multiple requests at the same time. It simply depends on the thread, from which the call is sent.
Any hints are appreciated very much.
Thanks!
Thilo

We are a step further now...thus the problem to be solved changed a little bit.
The former assumption, that connecting to the DDE server does only work from the main thread was false. It only seemed like that, because we called System.loadLibrary() to in the main thread to load the DLL . In fact, the connection to the DDE server works from any thread - you just have to make sure that System.loadLibrary() is invoked in this same thread.
This means: if System.loadLibrary() is invoked in the Event Dispatch Thread, we can call the DDE Server from this thread, which is what we primarily wanted to do. So our problem is solved.
Anyway, I made some more tests to find out, what happens if I start multiple threads, with each of them calling System.loadLibrary(). The result was, that only the first thread is successful. This means: the first thread, which loads the DLL is the only thread that is able to connect to the DDE server. All other threads won't get a connection.
What could be the reason for that?

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