Not all Mopac-Maps are displayed in Oruxmaps

Hi
I downloaded a map with Mobac 1.8 and installed it in a Samsung Galaxy S1.
For the map i chose level 13 and 14.
Mobac shows, that for level 13 one file was sufficient, but level 14 needed two files named
SR 14 (0) and SR 14 (1).
When i tried to display the map with Oruxmaps level 13 was shown but level 14 not.
The display stayed empty.
The file-manager OI shows that both levels had been stored completly in the smartphone.

Can anybody tell me what has to be done?

Thanks for your help.