OpenVPN works with WiFi but not with 4G

Hello guys,

I am able to connect to an OpenVPN server using the softwares Feat VPN or "OpenVPN for Android" using my wifi connection. However, I cannot get connected to the vpn server through 4G. I have a Galaxy S II x and I am using the mobile browsing service from Petro Canada/ Speak out.
I would really appreciate if someone could help me solve this problem.

Thanks a lot!