error :Method 'DocumentHTML' of object 'IDHTMLEdit' failed

hi for every one

i using program for send e-mail

and i use 'IDHTMLEdit' to load text file with message

but after i load file and run program ,compiler show following messagebox:

Run-time error'-2147418113(8000ffff)':
Method 'DocumentHTML' of object 'IDHTMLEdit' failed

i want to help me to solve problem because i want to load text file with my message .

note : i use following function :

Code:

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Sub SendEmail(MailServerName As String, FromName As String,FromEmailAddress As String, ToName As String, ToEmailAddress As String, EmailSubject As String, EmailBodyOfMessage As String, htmlBody)

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and use next code for sending and loading :

Code:

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dlgFile.FileName = "c:\COA.log"
    htmlBody.LoadDocument dlgFile.FileName
    SendEmail "smtp.gmail.com", "Mohammad Ali", "[email protected]", "SADAD", "[email protected]", "Read Message", " COA", htmlBody.DocumentHTML
       
    StatusTxt.Caption = "Mail Sent"
    StatusTxt.Refresh
    Close
    MsgBox "COA_ ", vbExclamation, "Sending Status"

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