Problem in swap DateTimePicker values

[Dasensa]

Hi, I have two DateTimePickers to determine date range, with their names are dtStartDate and dtEndDate.
I want to swap their values if dtStartDate value > dtEndDate.
In dtStartDate_ValueChanged event, I only write codes as follows:

if (dtStartDate.Value > dtEndDate.Value)
{
     DateTimePicker dtTemp = new DateTimePicker();
     dtTemp.Value = dtStartDate.Value;
     dtStartDate.Value = dtEndDate.Value;
     dtEndDate.Value = dtTemp.Value;
}

When I ran the code, I got both values are equal (dtStartDate value = dtEndDate).
Step by step debugging showed their values were swapped.
But when the debug step exit from dtStartDate_ValueChanged event, both values became equal.
I guess it happened because of the value passed as reference, not as value.
How to fix it, so I can swap both values?
Thanks for your help / direction.

[cocoa2135]

You can use dtStartDate_CloseUp;

after performance dtStartDate.Value = dtEndDate.Value;
another dtStartDate_ValueChanged occurs