TD 4.2, Problems with playback file

[MK-IBS]

Hello,
we have a problem that our application sometimes causes a not reproduceable error if the customer is working with it.
Because this error did not appear in our installation we decided to sent the customer an application compiled in playback-mode in order to generate a playback file (*.REC) to analyse the problem and find out in which line of the code the application causes the error.
The error appeared at the customer again and we got the playback file from the customer.
But when we load it into the related application it starts and the 'Continue' button is activated but if we click on 'Step into' it does not step through the code.
During debugging in playback mode we can click a few times on 'Step Into' but that causes no action which is visible in the source code (no stepping through the lines of the code).
After clicking for the 8th time on 'step into' the Application crashes like it does at the customer...

error message: 'SQLWindows hat ein Problem festgestellt und muss beendet werden....'

What can be the reason that playback mode could not show the steps which are passed in the source code !?

If you like to have a look on this problem please use the following FTP-link where you will find a zip-file (Playback-Problem.zip) including the application (merged APP), the related playback file and images of error message

ftp://exchange:ibs@ftp.ibs-ag.de/

thanks in advance & best regards
Markus