Outlook Client Cannot Autodiscover Exchange 2013 CU10 in Coexistance with Exchange 2007

I have an issue with Outlook Clients when adding a new mailbox that is hosted on Exchange 2013 in a coexistence with Exchange 2007 (on premises). The co-existence is temporary until all mailboxes are migrated to Exch2013 and then will decommission exchange 2007. The current environment is as follows.

Exchange 2007
- 1x CAS (Windows server 2003 Ent 64Bit)
- 2x Mailbox Severs (DAG enabled) (Windows 2008 Ent)

Exchange 2013
- 2x CAS (Win2008 R2 Standard)
- 3x Mailbox Servers (DAG Enabled) (Win2008 R2 Datacenter)

- Barracuda Load Balancer setup for mail flow and CAS HA.
- 1 Forest and 1 Domain

Overview of the current Exchange Status.
- Emails are accessible internally and externally via OWA and Outlook client on both exch2007/2013 servers.
- Adding a new mailbox in outlook onto Exchange 2007 resolves to the correct CAS (Ex2007) successfully.
- Adding a new mailbox in outlook onto Exchange 2013 gives the error (refer to attachment)
Adding outlook client was working perfectly during the initial configuration and testing. However, after installing Exchange 2013 CU10 on all the Exch2013 servers, I started to encounter the error.

It could be a CU10 bug but tried every information I can find on the web but none works.

Would appreciate a resolution please.

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Attachment?  Did you forget to attach something?
daltroneexAuthor Commented:
Yes, sorry. I've attached it here.

What I have done so far:
I removed the Autodiscover Virtual Directory successfully from all Exch 2013 servers using
Remove-AutodiscoverVirtualDirectory -Identity "CAS01\autodiscover(autodiscover.contoso.com)"
However when I try to recreated it using this command.
New-AutodiscoverVirtualDirectory -WebSiteName "autodiscover.contoso.com" -WindowsAuthentication $true -DigestAuthentication $true

I'm getting this error.

Argument: -Role ClientAccess
    + CategoryInfo : InvalidArgument: (:) [New-AutodiscoverVirtualDirectory], ArgumentException
    + FullyQualifiedErrorId : [Server=mbxserver,RequestId=f83afe9f-493c-4f78-a757-d2cd9a98cddb,TimeStamp=25/09/2015 12:46:32 AM] [FailureCategory=Cmdlet-ArgumentException] 8747659D,Microsoft.Exchange.Management.SystemConfigurationTasks.NewAutodiscoverVirtualDirectory
+ PSComputerName  : casserver01.domain.local

I'm not able to recreate the autodiscover VD. Is there any other way to created the VD?
daltroneexAuthor Commented:
I ended up rebuilding the 5 servers OS and exchange with CU7 in a sequential order to avoid downtime.

Doing migrations of 4000+ mailboxes now.

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daltroneexAuthor Commented:
I resolved it myself.
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