I have a IPK that has a license for 48 ports. I currently have 1 - 16ESIB and E, 1 - 8 ESIB, 1 - 8COI, 1 4port voicemail card. These cards equal out to 24 digital, 8 coi, 4 voicemail ports = 36 ports. The system will not let me add another 8 esib card. I have slots 3,5-7 available. I get an error when I try to install the card. I have tried resetting the system. any suggestions as to why I can not add the card?