Hi Kada,
It looks like this update lost its association to software release. It should be associated with Windows XP(x64).
Similar issue was discussed here: http://www.symantec.com/connect/forums/smp-71-sp2-staging-ms12-034-fails
You may create ticket to support who can investigate this issue deeper or you may try the following:
1. Check Windows XP (x64) in Vendors and Software tree
2. Disable revise task(if it is enabled) in order to prevent modifying your existing SWU policies and downloading not required Windows XP updates
3. Run PM import task with selected Windows XP (x64). [After this lost association should be restored]
4. After PM Import is completed uncheck Windows XP(x64)
5. Enable "Delete previously download data for excluded vendors, releases, languages..." settings on PM Import task page. Please note that existing patch data related to all exluded vendors/software/languages will be removed with next PM Import task.
6. Run PM import with unselected Windows XP (x64). [After this software update resource WindowsXP-WindowsMedia KB2834902-x64-ENU.exe should be deleted because Windows XP(x64) is excluded]
7. Revert all PM Import task settings(Revise task, Delete previously download data for excluded vendors, releases, languages ) to yours.
Thanks,
Roman