powering an old 9V multimeter with a 6x AA battery pack
As others have said, you've undoubtedly got the polarity wrong (hopefully not fatally, but it's possible), but also note that you have a bit of a dangerous setup there. The batteries are tied to the unknown voltage being measured so the battery is normally contained completely within an insulated box. For example, a cheap B&amp;K meter I have in front of me carries this warning: 

WARNING: To avoid electrical shock remove test leads before opening case. 

Your case, as shown, is effectively open all the time. As well as shock, you could damage something electrically if the battery connections shorted to something.