Help with the steps to decomision a Exchange Server 2007

i have 2 servers with exchange 2007 SP1(NewOne and Oldone), the plan is decomision one of them, so we move all the mailboxes and point public folders to the server New Server and we are trying to uninstall the Exhchange from the old server.

First we start the uninstall process and we were able to unistall everything except the Mail Role

We get an error "The public folder database contains folder replicas" so.. we read the manuals and found te moveallreplicas.ps1 script to start moving some replicas and later be able to remove the database and complete the uninstall but...

moveallreplicas.ps1 -Server Old -NewServer New

return this errors
 
Set-PublicFolder : Cannot save the object ´\NON_IPM_SUBTREE\Events Root´. Please make sure that you specified the correct identity and that you have the necesary permissions to save it.
At ReplaceReplicaOnPFRecursive.psq:147 char:24

same for:
\NON_IPM_SUBTREE\OWAScratchPad
\NON_IPM_SUBTREE\schema-root
\NON_IPM_SUBTREE\StoreEvents

both Servers are Exchange 2007, one time ago in the same domain forest exists a Exchange 2003 but it was not upgraded was decomisioned complety before start with Exchange 2007

we are using Administrator Account so must have all permisions but...