I believe the issue that was being experienced with this thread was that the supporting wagmp_maps.js file had a missing entry for the map that was on the page. So for example if you have a map identified as map 3 on your page and in this file there was no reference to map 3 then it will not show.
Do you have a link where this can be seen? Are you working with php? If so a php page that produces an error will come up blank if error reporting is turned off. If this is the case you can enable error reporting on the page with the map by adding in this code:
Please post back with some more info and a link if you can so that we can take a look at this with you.