How to upgrade Richmail from version 6 to 9

I have download RichMail for version 9 . currently we are using version 6 . i am getting an error when i try to upgrade it through service center . error is :
There was an error validating the extension: System.TypeLoadException: Could not load type 'OutSystems.NssRichMail.RLPop3MailRecordList' from assembly 'OutSystems.NssRichMail, Version=, Culture=neutral, PublicKeyToken=null' because the parent type is an interface.
 at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type)
 at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase)
 at System.Reflection.Assembly.GetType(String name)
 at OutSystems.HubEdition.ServerCommon.Extensions.ExtensionValidator.CheckExtensionConsistency(String temporaryXIFPath, String temporaryResourcesDirPath, String anonTypesXml).

Please give me a solution to getting this done.

Hi there Prassin,

I believe it's best for you to reach out to OutSystems Support to get help.