i am creating an email function to send and received email but there is an error, the error is

Unable to cast COM object of type 'System.__ComObject' to class type 'System.Net.Mail.MailMessage'. Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.

anyone can figure out what is my problem with this error message?