Missing bass drum on mixdown - Help Please!

I posted this in the Cubase forum a few days ago with no reply. I am using Groove Agent 1, I assume this would be the same in either version.

Cubase 6.0.5 on win7- 32

I created a simple 2 measure drum groove I need to use for a click track for some recording. I am collaborating with someone that does not have Cubase so I am exporting it as an MP3. When I export it and listen on another computer I do not have the bass drum, just hi-hat and snare.

Any help would be greatly appreciated