Cannot get code to not be nothing after .Find

I am trying to code a macro that will take an ID number that is somewhere in the file name and then find the matching subject number in Column A of a master sheet, where it will then offset and add to that row. There are two files, one called InterviewData10**.xlsx and SCIDdata10**.xslx with the asteriks representing two numbers. I had success with InterviewData using this code:

InterviewFile = Dir(FileDir & "InterviewData*xls*")
Do Until InterviewFile = ""
    DoEvents

    Set Interview = Workbooks.Open(FileDir & InterviewFile)

    Dim InterviewFilepath As String
    InterviewFilepath = Interview.Name

    Dim SubID As Variant
    Set SubID = Master.Sheets("Data").Range("A:A").Find(what:=Mid(InterviewFilepath, InStrRev(InterviewFilepath, "\") + 14, InStrRev(InterviewFilepath, ".") - InStrRev(InterviewFilepath, "\") - 14), LookIn:=xlValues, LookAt:=xlWhole)


    If Not IsError(SubID) Then
        Interview.Sheets("HAM-D").Range("B23").Copy
        SubID.Offset(0, 28).PasteSpecial xlPasteValues
        Interview.Sheets("PANSS").Range("C9").Copy
        SubID.Offset(0, 29).PasteSpecial xlPasteValues
        Interview.Sheets("PANSS").Range("C17").Copy
        SubID.Offset(0, 30).PasteSpecial xlPasteValues
        Interview.Sheets("PANSS").Range("C34").Copy
        SubID.Offset(0, 31).PasteSpecial xlPasteValues
        Interview.Sheets("YMRS").Range("C13").Copy
        SubID.Offset(0, 32).PasteSpecial xlPasteValues
    Else
        Master.Sheets("Data").Range("A" & Rows.Count).End(xlUp).Offset(1, 0) = SubID
        Interview.Sheets("HAM-D").Range("B23").Copy
        SubID.Offset(0, 28).PasteSpecial xlPasteValues
        Interview.Sheets("PANSS").Range("C9").Copy
        SubID.Offset(0, 29).PasteSpecial xlPasteValues
        Interview.Sheets("PANSS").Range("C17").Copy
        SubID.Offset(0, 30).PasteSpecial xlPasteValues
        Interview.Sheets("PANSS").Range("C34").Copy
        SubID.Offset(0, 31).PasteSpecial xlPasteValues
        Interview.Sheets("YMRS").Range("C13").Copy
        SubID.Offset(0, 32).PasteSpecial xlPasteValues
    End If

    InterviewFile = Dir

Loop

I tried this with the SCIDdata, however it is a lot more conditional than just copying and pasting. It has 1's that when in certain cells need to have a certain word put into the master file. This is the code I am trying to use:

SCIDfile = Dir(FileDir & "SCIDdata*xls*")
Do Until SCIDfile = ""
     DoEvents

     Set SCID = Workbooks.Open(FileDir & SCIDfile)

     Dim SCIDfilePath As String
     SCIDfilePath = SCID.Name


     Dim SubjectID As Variant
     Set SubjectID = Master.Sheets("Data").Range("A:A").Find(what:=Mid(SCIDfilePath, InStrRev(SCIDfilePath, "\") + 9, InStrRev(SCIDfilePath, ".") - InStrRev(SCIDfilePath, "\") - 8), LookIn:=xlValues, LookAt:=xlWhole)

     'Pulls Subject ID from file name and matches it to the existing one in master

        If Not SubjectID Is Nothing Then
            If SCID.Sheets("ALG. III").Range("L6") = 1 Then
                SubjectID.Offset(0, 1).Value = "BPI"
            ElseIf SCID.Sheets("ALG. III").Range("L7") = 1 Then
                SubjectID.Offset(0, 1).Value = "SM"
            ElseIf SCID.Sheets("ALG. III").Range("L9") = 1 Then
                SubjectID.Offset(0, 1).Value = "BP2"
            ElseIf SCID.Sheets("ALG. III").Range("L10") = 1 Then
                SubjectID.Offset(0, 1).Value = "Other BP"
            Else
                MsgBox ("Error: Please check SCID file before continuing")
                Exit Sub
            End If
        Else
           MsgBox ("No subject ID was found for this subject.")
        End If

    SCIDfile = Dir
Loop

When running the code is stopped when I do SubjectID.Offset.

In my efforts to debug, I have found the following:

The file is certainly opening, and data can be copied and pasted.

The mid function is grabbing the correct subject ID number from the name of the file.

It is not "nothing" because if I do simple functions (that do not involve SubjectID) after the first if statement, there is no error and the code will run properly.

When doing debug.Print, for some reason there is nothing in the immediate window. It does not recognize the SubjectID as a cell value, whereas when I do debug.Print on the SubID from InterviewData, it comes up with the ID number for the chosen file. Because of this, it is telling me that I am missing an object (error 91).

I am aware of the problem, but I have no idea how to fix it.