What's the trick to write a text file with vbscript?

===What's the trick to write a text file? ======
Microsoft VBScript runtime error '800a01a8'
Object required: ''
/aquarium/mysqlToXmlFile.asp, line 24

Code:

' VBSCRIPT
24: Dim myFile: myFile = Server.Mappath("aquariumBak.xml")
25: Set objFile = FileOs.CreateTextFile(myFile,True)

===.Or, this also does not work.================
Microsoft VBScript runtime error '800a0046'
Permission denied
/aquarium/mysqlToXmlFile.asp, line 22

Code:

21: Set objFSO=CreateObject("Scripting.FileSystemObject")
22: Set objFile = objFSO.CreateTextFile("aquariumBak.xml",True)