-VSS Copy Service in windows guest is in bad state, use: vssadmin list providers
-the application writer is in bad state, use (it´s ok if no errors appears): vssadmin list writers
-vmware vss componentes not installed/registered correctly, use: sc query vmvss
-tools not installed ok
---- VSSADMIN Commands Supported ----
Delete Shadows - Delete volume shadow copies
List Providers - List registered volume shadow copy providers
List Shadows - List existing volume shadow copies
List ShadowStorage - List volume shadow copy storage associations
List Volumes - List volumes eligible for shadow copies
List Writers - List subscribed volume shadow copy writers
Resize ShadowStorage - Resize a volume shadow copy storage association
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Take a look to this interesting post about VSS and SRM (Thanks @vmKen to sharing):
http://blogs.vmware.com/vsphere/2012/08/srm-5-1-and-vsphere-replication-as-a-standalone-feature.html