Problem with row coloring in qtableview

Hello,

I am using following code to assign data and color to contents of QTableView:

Code:

for(y=0; y<7; y++)
        {
            QStandardItem* item=new QStandardItem();
            if(y==6)
            {
                if(nepopolno)
                    item->setData("krizec",Qt::DisplayRole);
                else
                    item->setData("kljukica",Qt::DisplayRole);
 
            }
            else
                item->setData(ukaz.value(y).toString(),Qt::DisplayRole);
 
            item->setData(ukaz.value(6).toString(),Qt::UserRole);
 
            item->setBackground(Qt::red);
            model.setItem(vrsta,y,item);
        }

Variable y represents column as you can see. Problem I face is that only first column is colored. If I debug with debugger, then I see that item->setBackground() method is certainly called for every QStandardItem of model that is assigned to QTableView.
Any clues how to write this code correctly? Or is there some other issue with Qt?