Without knowing what your data looks like it's hard to tell. Generally, to
create a combination column-line chart, create a column chart first. Next,
select one of the series. Go to the standard toolbar and select Chart ->
Chart Type -> Line -> OK.
Alternatively you could create a line chart first. Next, select one of the
series. Go to the standard toolbar and select Chart -> Chart Type -> Column
-> Clusted Column -> OK.