Access VBA send mail corrupts PDF

I have VBA code that sends PDF documents, if I check the document before sending it looks fine but the recipient receives a corrupted version (Black lines and some pages completely black). BTW we use Exchange 2007

 Set objMessage = CreateObject("CDO.Message")  
    With objMessage
        .Subject = "Test"
        .From = "username@domain.com"
        .To = "username@domain.com"
                 
         objMessage.AddAttachment ("C:\Attach\sample.pdf")
 .Configuration.Fields.Item("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2     .Configuration.Fields.Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") = "xxx.xxx.xxx.xxx"
       .Configuration.Fields.Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = 2
        .Configuration.Fields.Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = "25"
        .Configuration.Fields.Update
       
        .Send