Warning: array_key_exists() [function.array-key-exists]: member list error

[rootsxrocks]

When I sort the member list by the amount of money members have it seems to work until I switch pages and then I get

Warning: array_key_exists() [function.array-key-exists]: The first argument should be either a string or an integer in [path]/dbtech/credits/credits_vbulletin.php on line 41

I can't really tell if this is causing some functionality issue but I figure it might be a little bug I should report. I can look at money amounts in vbookie and other ways so this isn't really needed.