Arguments are of the wrong type, are out of acceptable range, or are in conflict with

Hello there
I have got a sp which take a datatype of @FaxDoc varbinary
Now I wanted to set the parameters from vba code the VBA Function as below:

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I debug the code when it come to .Parameters.Append .CreateParameter("@FaxDoc",advarByte, adParamInput, 10000, faxDoc)
It through increate data type.
What is the right data type should use to pass a value of faxDoc() As Byte