Fatal error: Class 'nodereference_explorer_plugin_content_nodereference' not found

Hello there,

I have installed the last 6.x-1.3 version in both development and production environments. I have tested it in development and works almost ok, but in production site, when I try to configure a node reference field I get this error mesage:

Fatal error: Class 'nodereference_explorer_plugin_content_nodereference' not found in /usr/home/xxx.com/web/sites/all/modules/nodereference_explorer/nodereference_explorer.module on line 227.

I have found a similar error on this issue queue, but the solution to this is not mentioned there (at least not one I could understand).

I have de-installed 6.x-1.3 version and installed node reference explorer 6.x-1.dev and still getting the error message.

I am not a savy php programmer so any help would be much appreciated.