I am trying to get EmailSendDefintion info through its ObjectID which is return by ET_Send log. However, due to some reason, part of the EmailSendDefinition can be retrieved which others are return null. In additional, When using SDK for send to dataExtension. I create unique emailSendDefintion for each of them through SDK. However, when I retrieved the send logging. Some of them send logging return null for the emailSendDefintion part. Can anyone help me to figure out what is reason to cause these issue. Thanks a lot!