For the verification, TransDEM looks for TrainzMeshImporter.exe in the folder you point to and if it finds the exe, it launches it and waits for the response. If this goes wrong for some reason, TransDEM may wait indefinitely.
You could check this by manually probing the exe, without TransDEM. Open a console window for the folder you unzipped the mesh importer to (Shift + Right click for the context menu "open command prompt here" in Win 7, not sure about higher versions, but "cmd" in the start menu should always work). Then run TrainzMeshImporter.exe from that console. You should get something like this:
Code:
E:\Programme (weitere)\Auran\misc\TrainzImporter_111019>TrainzMeshImporter.exe
Error: Missing parameters.
Usage:
TrainzMeshImporter [ options ... ]
Converts a mesh and animation data file
into Trainz compatible .IM and .KIN files.
Options:
-inFile <filename> Input file name
-outFile <filename> Output file name (extension ignored)
Uses inFile name if parameter is missing
-outputIM [true],false Output the geometry file
-outputKIN [true],false Output the animation file
-log <filename> Write log to file
-warnings [true],false Log warnings
-info [true],false Log information
-k Wait for key on exit
-ke Wait for key on error
-? Show this help screen