BB Bold :: 9900 - Sending Group Text (Only 8 Out Of 18 Receive Message)

I have a Bold 9900. Under "contacts" I have created a distribution list, mainly my baseball team so if a game is cancelled, I would like to address them all in one swoop. The problem is, only 8 out of 18 receive a text. I go to the "text message" icon, press the blackberry button on "compose text message". When it asks "To:" I select from my contact list, my baseball team.

Some of the entries on my list have an email address only while others have both. What do I have to do to successfully reach everyone on the list? Would it work better if it were only email or mobile addresses? Does it matter whether they are MTS or Rogers customers for their cell phones? Do I require to add 1+then the area code for the cell phone numbers?