Subclassing QSortFilterProxyModel

Hi folks!
I implemented a QSortFilterProxyModel sublcass and i overrode method bool filterAcceptsColumns(int source_column, const QModelIndex &source_parent) const,
all went well when i compiled my program but this method is never called.
Have i to override other methods?

I attached example files...
Thank you in advance. :D

It should be filterAcceptsColumn not filterAcceptsColumns.

Oops!
Thank you!!