Dashboard chart does not match filter when clicking through

Hi all

I have this Dashboard/Chart on the landing page that's been setup by someone else. the red bar does not show the correct number (shows 25 count here) as when I click through to the filter it shows more.

Shows 226 once I click though

Can anyone point me to how I can go about fixing this? I'm not too familiar with Dashboards or Charts so I would need a bit of detail here on how I can fix this.