Game exporting issue

Hi everyone,

I'm newbie in Unity, this is my third week on the job and the boss asked me to export an old Unity 2D project again. This project has 22 diferent levels (scenes) and uses UnityFacebookSDKPlugin. The game seems to work well in Unity but, when I export it, the game freezes when the forth scene starts (or when the third one ends). I think the problem might be in the Facebook plugin (something like the exported game cannot link with FB plugin) but I don't know how to check it. I tried exporting Web Player and PC platform with the same wrong results.

I know my explanations are not too concrete but there's nobody to ask here, because the people who developed the game have already left the company. Hope you can help me or tell me where the problem might be.

Thanks a lot!