Migration Office 2007 (Windows SBS 2008) to Office 365 failed

Hi,

I try to migrate since 1 week from an exchange 2007 ( OS: Windows SBS 2008) to Office 365.

I follow prerequisites bellow :
- Check exchange 2007 version : 08.03.0485.001
- install cerfificate SAN
- Check outlook anywhere ( problem with rpc over http which was in conflict with ts gateway, that can be solved after reinstallation of Rpc over Http and remove ts gateway on Windows SBS)
- Check Outlook connectivity from https://testconnectivity.microsoft.com/ => All is green
- Give the rights for admin exchange to all mailbox on exchange on premise


But the cutover migratation doesn't work, the error bellow appears : Object reference not set to an instance of an object appear for all the mailbox

Here results of powershell command :

On Exchange OnLine[PS] C:\[PS] C:\Users\Administrateur\Desktop>Test-MigrationServerAvailability -ExchangeOutlookAnywhere -Autodiscover -EmailAddress administrateur@domain.com -Credentials $Credentials

RunspaceId         : 4473ff68-84ad-4613-b2d2-a0067fe1f6b9
Result             : Failed
Message            : The migration service failed to detect the migration endpoint using the Autodiscover service. Consider using the Exchange Remote
                      Connectivity Analyzer (https://testexchangeconnectivity.com) to diagnose the connectivity issues.
ConnectionSettings :
SupportsCutover    : True
ErrorDetail        : Microsoft.Exchange.WebServices.Data.AutodiscoverLocalException: The Autodiscover service couldn't be located.
                        at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.InternalGetLegacyUserSettings[TSettings](String emailAddre
                     ss, List`1 redirectionEmailAddresses, Int32& currentHop)
                        at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetLegacyUserSettings[TSettings](String emailAddress)
                        at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.InternalGetLegacyUserSettings(String emailAddress, List`1
                     requestedSettings)
                        at Microsoft.Exchange.Migration.MigrationAutodiscoverClient.GetUserSettings(ExchangeVersion exchangeVersion, NetworkCredentia
                     l credential, String emailAddress, Boolean acceptUntrustedCertificates)
IsValid            : True
Identity           :
ObjectState        : New


I begin to desperate, Can you help me ?
Result-Connectivy.JPG