Automatic Litterbox Central

i've run approx 10 cleaning cycles and the level of the cleaning solution has not changed. i pulled the cartridge off and took a look but not sure what to look for. i know the cartridge cap is pierced b/c a small amount dripped on the floor when i removed it.

has anyone else had this problem? can you tell me what i should be checking for?

thanks in advance,
-crimius