[Plugin: Leaflet Maps Marker] No access

When i install the Plug-in all is ok. But when i update the Setting Page i got an error 503. And after this when i want go to “add markers” page, i got error: you have no permission to access this page.

After this i must delete the Plug-in.

Sorry i have german WP installed, i hope the sites and error messages are correctly in english.

http://ww.wp.xz.cn/extend/plugins/leaflet-maps-marker/