Calibre not sending APNX file

Hello all, i 've just noticed that when i use "Send to Device" my device doesn't get the apnx file and as a result i get no pagination:/ (nexus 4, amazon kindle reader 4.0.4.1)

Is the feature not supported for android phones?

I 've tried the steps Preferences->Plugins->Device Interface Plugins->Kindle Device Interface, checked that the appropriated options are checked..but no luck..
any help appreciated

Thanks