Align button inside cell table

Hello,

I added a button inside a cell table, but I don't get it align to the left (see the image , the add icon is displayed always on the right side of the cell)
My code:
        m_oComenziTable.addContainerProperty("+",Component.class,null);
        m_oComenziTable.setColumnWidth("+",10);
        m_oComenziTable.setColumnAlignment("+", Align.RIGHT);
        m_oComenziTable.addContainerProperty("Nr.",Long.class,null);
        m_oComenziTable.setColumnWidth("Nr.",40);

.....
Button oButtonAdaugaSubcomanda = new Button("");
                oButtonAdaugaSubcomanda.setDescription("adauga subcomanda");
                oButtonAdaugaSubcomanda.setIcon(new ThemeResource("../easyship/img/Add-icon.png"));
                oButtonAdaugaSubcomanda.setStyleName(BaseTheme.BUTTON_LINK);
                oButtonAdaugaSubcomanda.setHeight("16px");
                oButtonAdaugaSubcomanda.setWidth("16px");
                oButtonAdaugaSubcomanda.setData(oSubcomanda.getScoId());

...
m_oComenziTable.addItem(new Object[]{
                        oButtonAdaugaSubcomanda,

Thank you