Only possible to show data of one day (no replies)

Dear users,

I have the following problem with my piwik installation:

When i show the data of one day Piwik gives me accurate data of this day. When i choose a week or month in the date picker the system gives me no data after a certain date. Is this a known issue with a solution or is there someone that can help me with this problem?

Thanks in advance.

JRM