Sum function not working for me

Hi

I have created a sql query and need to get the total of the field:  CON.new_TotalNoofPlanMembers.
This field  can contains an integer value from range: 1-10.
I need to get the grand total of this field - my code is not working and I can't figure out how to get this working.

SELECT 
	CON.new_MembershipNumber			AS 'Membership ID',
	CON.FullName					AS 'Member Name',
	CON.new_SalesChannelOnlyforPrivateMembersName	AS 'Bll To Corp. Name',
	CON.new_TotalNoofPlanMembers			AS 'Total # Plan Members',
	(SELECT SUM(CON.new_TotalNoofPlanMembers)) as 'test'

FROM
	dbo.FilteredContact CON