As the error states: "Number of CMS-measured VDNs exceeds CMS administered maximum" -this has nothing to do with BCMS.
You need to take marcell55's advice and increase the data storage allocation.
On the VDN form, in the field 'measured' you have four options, none (self explanatory), internal (BCMS), external (CMS) and both (BCMS and CMS) - you can play around with these perhaps...