如何在DevExpress GridControl中填充最后一列的宽度？

I have DevExpress GridControl wich has 7 columns. I tried to expand the last column to the right, but nothing happens. Instead, the column stretches for some distance, and on the right edge of the grid, there is an empty column with no name, which can not be stretched.I have DevExpress GridControl wich has 7 column