When Backup Sharepoint 2007, with DPM 2010, it catalougues MOSS items every 24 hours , if you need to force this operation to be able to restore item you can use powershell command. http://technet.microsoft.com/en-us/library/ff634233.aspx. Note this operation happens out of band from the normal backup, sometimes it will fail even though the backup is successful.
 
I had the problem that I had created a backup but items were missing when i tried to restore, so i forced creation of the recovery point looked at the back, but no still no new item to restore.

I then found that a separate process performs the catalog of the items each day. Without this the list of items doesn't get updated, so even though they have been backed up they don't appear for item level restore.

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To force the Catalog Process
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this is how to enter the command, you must enter your datasource as variable, use the below
 
$pg1 = get-protectiongroup –dpmservername  yourdpmservername

Now run: $pg1

This will show a list of the protection groups, counting from 0 from the top down, make a note of the number of the line coresponding to the protection group you are interested in.

$ds1 = Get-Datasource –ProtectionGroup $pg1[x]
(where x is the line number you’re interested in)

Now run: $ds1
This will show a list of all the data sources. Counting from "0" from the top down. In my case the sharepoint farm protection object was number "11" so I then run this command putting the number 11 into the square brackets.
 
start-createcatalog -datasource $ds1[11]
 
DPM will start catalogue, wait for it to complete, then you shoudl be able to see your object for restoration.

Or, you may also run this command:

Get-ProtectionGroup yourdpmservername | get-datasource | where-object {$_.type -like "*sharepoint*"} | start-createcatalog

This will automatically run the createcatalog for any datasource matching "sharepoint", this command will show the catalog is running, but then a few errors, the errors are it trying to process a catalog update on something that is not a catalog, and can be ignored safely.