An infrequent but relatively common issue I've run into with Views is that when showing teasers, a common number of posts per page is 10; but when showing the single lines from the summary, 25 is much more common. But Views doesn't let you change the page size in summary view mode.

Note: If you don't know what summary view mode is, this page is a summary (what happens when a view has an argument and the argument is not present), while this page is the view when an argument is present.

If you want to have more (or fewer, tho that's unlikely) summary lines, this code in your 'Arguments Handling Code' section: