If it works in C2's preview mode but not after you export, either you are running it wrong (e.g. trying to run from disk, which won't work), you uploaded it to the server wrong (e.g. missing some files), or the server configuration is incorrect (e.g. missing MIME types). It's also possible it's a glitch caused by buggy graphics drivers. None of these are bugs in C2. Include a link to your published game for more information.