Path/File Access Error - Replacing text in xml with text from excel

As the title suggests, I have an xml file with many keywords (i.e. numbers 1-30) that I want to replace with other keywords present in an excel sheet (i.e. 31-60). 31-60 are present in the same row. I'm trying to open the xml file, find the location of 1-30 within the xml, replace them sequentially such that 1 is replaced with 31 and 2 is replaced with 32 etc. I then want to save the new file to a new file location giving it a new name. If possible, I want to loop the process for many rows of data so that eventually I end up with many xml files with different data in them. this is the code I have so far. Im also getting a Path/File Access Error on "Open sFileName For Output As iFileNum". I'd appreciate any help. Thanks for taking the time to read this.

Code:

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Option Explicit
Dim string_name(1 To 30) As Variant
Dim file_name As String
Dim sBuf As String
Dim sTemp As String
Dim iFileNum As Integer
Dim sFileName As String
Dim count As Integer

Sub replace_strings()

    count = 1
    Windows("Excel File Name.xlsm").Activate
    Range("B4").Activate
    file_name = ActiveCell
    Do While ActiveCell <> ""
        ActiveCell.Offset(0, 1).Activate
        string_name(count) = ActiveCell
        count = count + 1
    Loop
   
 


 
    sFileName = "C:\XML file location.xml"

    iFileNum = FreeFile
    Open sFileName For Input As iFileNum

    Do Until EOF(iFileNum)
        Line Input #iFileNum, sBuf
        sTemp = sTemp & sBuf & vbCrLf
    Loop
    Close iFileNum

    sTemp = Replace(sTemp, "bcsx", string_name(1))
   
   
    iFileNum = FreeFile
    Open sFileName For Output As iFileNum
    Print #iFileNum, sTemp
    Close iFileNum




End Sub

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