DateTimes with gaps

[Reginald]

Hello,

I am working on a problem that drives me crazy. I have some data like {Name, FinishedDateTime, Value,...}, and can look like
-> Test1, 2013-04-10 09:15:20, 1.5; 
-> Test1, 2013-04-10 09:16:56, 1.6; 
-> Test1, 2013-07-20 13:25:11, 1.3; 
-> Test2, 2013-04-09 14:47:23, 10.4;
Now I want to display these data in a LineSeries chart. Because I want to display just the dates with data I have chosen to use for the XAxis the XCategory as DataPointMember.
I also have a UserControl for displaying the dates on its own and has some special functionality what i can't miss. The picture In the attachment should give a glance how it should look like. The UserControl provides the VisualStart and EndDate, Periode and has methods to go to the next day, previous day,...
The problem is, how can I handle to get the columns of the chart aligned to the columns in the bar above?

Regards RB,