Thank you Marcel! I use the Chrome to view the report ,there is no error, but when I delete the date value and click the Refresh link, the date I filled appear again, I can't set the date field to null to have a new query?
I would ignore it or handle the null property in code if you can.
What is on that particular line 268? (when you generate the code of report on edit tab down there is another tab called code) Can you make some precautions if that property is null? maybe try to run it in other browser? to see what is the error.