You are getting error messages like these:
S: Preload (36120002): Loading Qt Wrapper failed: Invalid access to memory location."
S: Preload (36120002): Loading Qt Wrapper failed: Unzulässiger Zugriff auf einen Speicherbereich."
This could be caused by an incompatibility in the application that conflicts with the transparent hooking mechanism provided by Squish.
Use Squish's built-in hook in the Qt application. This is explained in the manual's Using the Built-in Hook section.