In a new translation, I translated one plural sentence and wanted to save. I am told: You are trying to create an empty mo-file without any translations. This is not possible, please translate at least one entry.
If I translate one singular word, I can save.
see: http://www.diigo.com/item/image/1eygw/j7nr
http://wordpress.org/extend/plugins/codestyling-localization/
After donwloading "Redirection" Plugin, I did create a new german language file, did a rescan an opened the editor.
Than I did switch to plurals, entered both phrases and pressed the save button. All work fine no warning has been issued.
So make it short, i can't reproduce the error you described above. I have no idea, why this happens at your system. This warning will only be issued, if you press generate mo-file in case the entiered translation file is empty. But also generation of mo-file with only this plural editing works as expected at my machines.
hm, you took the exact same steps as me. if you can't recreate it it must be a problem in my environment.
never-mind.
after translating a few singular words I could save.
Just thought I'd mention it in case it was not related to my server.