Playing MKV file with DirectShow filter installed

Hi

I'm having an issue playing and mkv file using the player with DirectShow/AC3 filter installed,Its a Win7 SP1 64-bit OS.

when i try to play it I get the error below

Unsupported error

this video is in an unsupported format and can not be played without installing additional directshow filters.

I've tried uninstalling and re-installing the Divx player and the ac3 filter and re-installing them but now luck, The player is set to run as administrator and i've tried to run it in compatability mode(XP SP2/SP3 and Win7) but now luck

Please help, its driving me nutz