if (mOverlayReader->GetLastError().size() == 0) {
for ( unsigned int i = 0; i < mSlicers.size(); i++) {
mSlicers[i]->SetOverlay(mOverlayReader->GetOutput());
if (mOverlayReader->GetLastError().size() == 0) {
for ( unsigned int i = 0; i < mSlicers.size(); i++) {
mSlicers[i]->SetOverlay(mOverlayReader->GetOutput());