Split Report Data by Time

Hi All,

I've got a problem with a WEBI Report. I'm trying to split the report's data by time.

In my report I have a tracking point date dimension that returns a data in this format: 18.08.15 09:06:14

I've created a variable "Hours by Tracking Point" that has this definition: =FormatDate([Tracking Point Date];"HH:mm")

Now I've duplicated the main report, and I filtered the new one using this variable.

Hours by Tracking Point BETWEEN 08:00  AND 09:00

The problem is that the only way that the filter works is if I select the values in list. If I try to type manually the time the filter doesn't work.
(But I need to type manually the times)

I've attached a screenshot.

I tryed also to use a different definition for the Hours by Tracking Point, converting the date to a chart and using the substring, but I've the same problem.