Need help with a Report in CR 2008

Scenario:

I have an assignment field that people assign people to work on the ticket. The ticket can have multiple of single assignments, meaing how many technicians are assigned to the ticket. I am trying to print records/tickets that only have a single assignment/technician to the ticket. Is it possible to isolate these tickets with a group formula or somthing. My current report is printing single and multiple assignment tickets, I only want single assignment tickets.

Here are my report table/fields:

The open date field is from table/field: CallLog.RecvdDate

The ticket number field is from the table/field: CallLog.CallID

The 1st Level assignee field is from the table/field: Asgnmnt.Assignee

The Date Assign field is from the table/field: Asgnmnt.DateAssign

The Time Assign field is form the table/field: Asgnmnt.TimeAssign

The Ticket Owner field is from the table/field: CallLog.Tracker

The Group Name filed is from the table/field: Asgnmnt.GroupName

This is how these two tables are related: CallID and DTLastMod

Sample Data:

Open Date     Ticket #          1st Level Assignee     Date Assign     Ticket Owner     Group Name

2013-12-01     1125474          Mel Limm                 2013-12-01        LIMM01              BWHelpDesk

Here's the group selection formula I am using: Count ({Asgnmnt.Assignee}, {CallLog.CallID}) = 1

Its not working, still including tickets with multiple assignments.

Can someone help?

thanks.

G.