Charger always falling out of USB Port on T-Mobile Galaxy S2 when case is on.?

[Liberal]

Its a case made of plastic, I think its a TPU. Its black. The problem is that the charger falls out of the case while charging my phone.

Pictures of the case

http://s1300.beta.photobucket.com/user/Liberal_Kazem/media/Picture65_zps571e3723.jpg.html

http://s1300.beta.photobucket.com/user/Liberal_Kazem/media/Picture64_zpsba4b40f3.jpg.html