Proxyaddresses

Powershell v3.0

Currently having an issue when trying to replace proxyaddresses.

1st I get the proxys
$proxys = (get-aduser $username -properties proxyaddresses).proxyaddresses

Then I change the users proxyaddresses through ADUC

I then run the above command again and compare to $proxys to confirm changes have been made

Then
set-aduser $user -replace @{proxyaddresses=$proxys}

This leaves me with no addresses in proxyaddresses. If I then run
get-aduser $username -Properties proxyaddresses | select proxyaddresses
the result is

proxyaddresses
--------------
{}

This should be a relatively simple task yet I cannot seem to get it working.

Any ideas on where I'm going wrong ?  Using PS3.0.

I can complete the task successfully with the Quest cmdlets but am trying to use the ActiveDirectory Module more and more and ween myself off Quest.

Thanks in advance