Document Migration From One environment to another

Hi All,

I like to move all the documents (that has been uploaded by end user )of an application from old Prod to new prod environment. So I create a separate App package ABC DOC Migration and add the parent folder (where documents uploaded by end user are stored) by selecting the option "ADD EXISTING" -> "Folder Contents". Most of the document had been exported successfully but some of them are not.

Those documents that were unable to be exported has folder structure - PARENT->ABC->CHILD. But Some of the documents having same folder structure has been moved successfully. 

While going to the application and the folder structure I am not able to see the document. From Object view searching by Doc Id I am able to see it.

Please help me why I am unable to export.

Thanks In advance