PyQt QSortFilterProxyModel mapFromSource() Help

Hello, I fairly new to PyQt and I'm struggling with a problem and I'm hoping someone might be able to help me out...

I have a model that is setup for use in a tree view, and I want to use a proxy model to reorganize the tree model for another view. When using the mapFromSource() method I keep getting invalid indexes. After some debugging it seems like every index which interates through this method is the root index. Can someone explain to me how to use mapFromSource() in PyQt?

Thanks