TimeAccounting 2.1.1 in OTRS 3.1.1 AutoComplete not working

[marv]

After upgrading from 3.0.x to 3.1.1 under Windows we encountered a problem in the time accounting module.

When the Autocompletion is enabled then we get a JS error as shown in the screenshots (taken from chrome, right and opera left).
This error occurs in all browsers.

Did anyone else get this error? And is there a way to fix this?

(This is a clean install with the new 'var' folder)

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The System is:
Windows 2k8 r2
OTRS 3.1.1
TimeAccounting 2.1.1

Also installed:
FAQ 2.1.1
SystemMonitoring 2.3.1
Support 1.3.2