Today I created a new tab with sample data. The dates where e.g. 21.10.2014. What QS did is putting antoher date in the example from above the 20.10.2011. I don't know why and I don't know how to solve the problem
Please post an example source file and qlik sense app that demonstrate the problem. Unless we can see what data you are using and what you're doing to it in the script we won't be able to tell what's going wrong.
I found coinsidently the reasen. While creating a sample file it suddenly worked. The only difference in the sample was, that I just had 1 column for a date. In my original file I had two columns next to each other with the same dates. For whatever reason QS wasn't able to load the correct dates. Each column was loaded and had dates but the wrong ones... ??