Thanks for your reporting. To perform more accurate analisys, please send me your map so I can work with the same scenario. If the map is heavy you can use one of the free web service to send big attachments. Send to this email email@example.com Many thanks.
The error occurs when no DEM data are available. I've fixed the bug. You'll find it fixed in the next version of OkMap. But if you go in the official repository of DEM data at http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/Eurasia/ you'll note that latitude greater than 60 doesn't exist.