Print out to Excel

How do I print out to Excel? Where are my mistakes?

exl = actxserver('excel.application');

    exlWkbk = exl.Workbooks;
    exlFile = exlWkbk.Open(['C:/Documents and Settings/path/Kerr.xlsm']);
    exlSheet1 = exlFile.Sheets.Item('Sheet1');
    exl.visible = true;
    n=2
    for l=1:4
        for k=1:4
            for j=1:4
                for i=1:4
                    n=n+1
                    exlSheet1.Range(['B' num2str(n)]).value = "RC(" & i & "," & j & "," & k & "," & l & ")=" & Riemann(i,j,k,l)
                end
            end
        end
    end
    exlWkbk.Close;
    exl.Quit;