Windows 7: Problem with DIAMOND XS 5.1/16 bit Sound Card

Hello there
I have DIAMOND XtremeSound 5.1/16 bit Sound Card and I am using Windows 7 Ultimate 64bit , overall I like it but I have a very small issue.
I am getting sound only from one outlet/inlet
Sound card have 3 outlet - Pink - Black and Green
Sub have 3 cables - Pink - Black and Green
Right now I plug cables from subwoofer to my sound card as color coding. If I play any stereo files all speakers working fine. If i play 5.1 movie or sound file than speakers are not working.
If I run test utility to see if all speakers working at that point I am getting sound only from Front Left, Centre and Front Right speakers.
I did some test to see if sound card defective or connection inside subwoofer
here my test result:
If I take pink cable from my subwoofer and plug it to pink input on SC result NO SOUND
If I put pink cable to Green and Black input on SC result NO Sound. same result with Black cable.
I am getting sound only with Green cable and if I plug it to Green input on Sound card. If I use Green cable and plug it to Pink or Black input result NO Sound.
At this point I am not sure its defective Sound Card, Subwoofer internal connection or Driver issue (I am using latest driver from http://www.diamondmm.com/XS51.php
Please let me know if you need any further info

Thanks for helping me

WOW ....... more than 250 person view but no suggestion or question. Come on guys I need your technical help.
Please help.................