Bobcheese is probably correct - you may not be able to tenantize a VM port.
Do us a favor and take a screen shot of your mailbox 105 and let us take a look at it.
Or better yet, use PSR from your PC, log into your 3300, edit extension 105 then edit mailbox 3 and post it here. We'll take a look to see if there is something obvious.
Ralph