Excel VBA, C-API Problem with DAQmxLoadTask

Hello,

ich have a problem using the DAQmxLoadTask funktion. I have a task which I created in the NI-MAX. The device is connected and I can execute the task in the NI-MAX.

Now I'm trying to access that task from Excel via VBA. I've set the reference to the NI C-API

but the following code always produces the error -200089, which means "Task name specified conflicts with an existing task name."

What am I doining wrong?

With kind regards,

Alex