Kb2804579 - Understand the need of this update

I choose five computers and create a teste group to test new updates.

4 computers windows 7 - 64.

1 windows xp.

I approved  this security update kb2804579 - .Net Framework 3.51 on windows 7 and windows Server 2008n R2 SP1 for X64-based System for this test group.

Updates superseding this update: none

Updates superseded by this update: none

I generate a report - Computer Detailed Satus Report for this security update in this test group:

The Result

For three win 7 - 64 bits - computers - status - Not  Applicable

For  1 win 7 - 64 bits - computer - status - Installed.

I really do not understand why This happened.

This update don´t have a superseding update and it is a new update. So because of that I thougt all the computers win 7 - 64 would install this update.

Why only one installed ?

Or it is a problem or I really isn´t understand the wsus operation.

Some comments it will be welcome.

Lyra