Displaying just the files with correct extension

Question

I'm trying in QFileSystemModel display just files with extention *.txt and the other types shaded/grayed out:

• proxy_ is of type QSortFilterProxyModel

• model_ is of type QFileSystemModel

Here's my code:

proxy_->setFilterWildcard("*.txt");  
proxy_->setSourceModel(model_);
model_->setNameFilters(QStringList(proxy_->filterRegExp().pattern()));
model_->setNameFilterDisables(true);
sel_model_ = (new QItemSelectionModel(proxy_));
treeView->setModel(proxy_);
treeView->setSelectionModel(sel_model_);

...but by doing so nothing is shown in my view. Anyone knows what I'm doing wrong?