Having problem with period result that mention -1 Night than 1 Night after selecting two dates from different months

[Zemed Yaucif]

As we are an Hotel and we have a reservation page, the customer have the choice to select the date of check in and check out in the same month or he can select the check in for example in the end of month june but the check out will be in the first july.

After making a test within the same month which was Ok, the result was not correct after making a test with 2 different months like June and July

Based on the below example. Instead of getting only 3 nights, we got Minus -27 Nights, is there any solution for that problem? Thanks

Check-in :;: 28-06-2013 07:41:15PM

Check-out:: 01-07-2013 07:41:27PM

Period :;: -27    Night(s)

Room Type: Suite