Hello, Probly!
First of all, Welcome to OTLand!
Then, I would like to tell you that in the future, I would really advice you to get known with the search function, as it always helps you in case you know how to use it in a proper way!
As well, you have to learn where to place such posts, but as only search for the map, this could be placed in perhaps, Mapping Support thread in the Mapping Showoff board;
http://otland.net/f57/mapping-support-29945/
Else you can try to use the usual Support board, in the OpenTibia Section here;
Support
...... Now!
I'm going to help you out with your issue; well well. An OTBM file, with this class. The real tibian map, is very hard to just switch OTBM file, as it contains extremely much other files, for example scripts. And when it comes to scripts, the following server you are using, so called "Naxxed OT" perhaps doesn't work with eachother, as they might have been compiled in different ways.
But you may always switch the complete system, to TFS, as it's the most stabilized distrubtion out in the community, and that there's a released distrubtion that uses a real tibia map, that will fullfil your wishes, for sure! You can find it here:
http://otland.net/f465/8-54-frankfarmers-real-tibia-project-epic-release-full-zao-link-61247/
I really think you get my point, in how to behave here on OTLand! You did not do anything wrong, as you just joined I can see. But in the future, try to think about where to place your posts / thread. And I as well hope that I helped you with your problem.
Kind regards,
Siramix!