VBS replace and write - vbscript

Question

Start of that I'm not that good with VBS but trying to learn.
Right now I have some difficulties with writing replace to a text file.
What I want to do is to search for the text "VGML", when this is found check on same row if there is a "STML" if so, this should replaced with " " to not mess up the positions in the file. And finally, if "VGML" is found without the "STML", the "VGML" should be removed.
I got so far when using echo I can see that the code does what I want, but writing to file mostly get me a empty file where the code removed everything.
Could anyone put me in the correct direction?
Here is the code:
Const ForReading = 1
Const ForWriting = 2
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objFile = objFSO.OpenTextFile("C:\Script\RemoveSTML\testFiles\test.txt", ForReading)
strEMTY = " "
strSTML = "STML"
strVGML = "VGML"
Do Until objFile.AtEndOfStream
strLine = objFile.ReadLine
If InStr(strLine,strVGML)>0 Then
If Instr(strLine,strSTML)>0 Then
strLine = Replace(strLine, strSTML, strEMTY)
wscript.Echo strLine
Else
strLine = Replace(strLine, strVGML, strEMTY)
wscript.Echo strLine
End If
End If
Loop
objFile.Close
Set objFile = objFSO.OpenTextFile("C:\Script\RemoveSTML\testFiles\test.txt", ForWriting)
objFile.Write strLine
objFile.Close
Wscript.Echo "done"
Thanks for your help! For giving me a kick in the correct direction!

Answer 1

In the loop, you read each line of the file and you write it into the variable strLine.
After that, you replace "SMTL"/"VGML", but after that, you're doing nothing with the content of strLine - you just replace it with the next line from the source file in the next loop.
Only at the end, you write strLine to the file once - but in that moment, strLine contains only the last line from the source file.
Solution: you can either write into the destination file inside the Do...Loop (but I'm not familiar with VBScript, so I don't know if/how to do this) or you can use a second string variable where you append strLine inside the loop but after the replacing...like this:
strFinal = strFinal & strLine
At the end, you write strFinal to the file, not strLine.