SUM Discrepancy

Hi to all once again. I thought I had resolved this issue but the addition of more data has found a floor in my design.

I have a small DB I intend to use for auditing my companies hardware / software.

frmComputerSoftwareAllocation: Allows me to allocate software / software licenses to computers.

Process: I select the computer I wish to allocate software to:
'computerID'. I then select the software 'cboSoftwareID' and then allocate
a license 'cboLicenseNum'.

As you know there can be multiple license keys for any one instance of software. So this leads me to my problem.

qryLicenseAllocated

Software ID of 32 = Microsoft Office Professional Edition 2003
1 * Volume License = 10
1 * OEM License = 1

Problem: As a test I alocated 1 volume license and the 1 OEM. When I ‘sum’ the number of licences from tblComputerSoftware instead of the query returning the desired result:

Microsoft Office Professional Edition : Licences Purchased 10 – Allocated 1
Microsoft Office Professional Edition : Licences Purchased 1 – Allocated 1

I get:
Microsoft Office Professional Edition : Licences Purchased 10 – Allocated 2
Microsoft Office Professional Edition : Licences Purchased 1 – Allocated 2

I can see what it is doing but after a long day getting this far can not see how to resolve it!!
Help very much appreciated.
Phil.