Hi I wrote a code to open a file name which contains buoy1xxxxx 

ub OpenTextfile()
    Windows("hello world.xlsm").Activate
    Sheets("User Input").Select
    Dim FilePath As String, fileName As String
    FilePath = Cells(2, 2)
    fileNameBuoy1 = Dir(FilePath & "Buoy1*.xl??")
    Application.ScreenUpdating = False
    Application.DisplayAlerts = False
    

  
    
Do While fileNameBuoy1 <> ""

    Workbooks.Open (FilePath & fileNameBuoy1)
    Sheets(1).Select
    Columns("A:A").Select
    
     Selection.TextToColumns _
      Destination:=Range("A1"), _
      DataType:=xlDelimited, _
      TextQualifier:=xlDoubleQuote, _
      ConsecutiveDelimiter:=False, _
      Tab:=False, _
      Semicolon:=True, _
      Comma:=False, _
      Space:=False, _
      Other:=True, _
      OtherChar:="-"
    Cells.Select
    Selection.Copy
    
    

Windows("hello world.xlsm").Activate
Sheets("Hello World").Select
Range("A1").Select

Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
        :=False, Transpose:=False
Range("A4", Selection.End(xlDown)).Select
Application.CutCopyMode = False
    Selection.NumberFormat = "0"
    

Workbooks(fileNameBuoy1).Close False

Call lookupHs24Hr
Call lookupHs48Hr
Call lookupHs72Hr
Call lookupHs5Days
Call lookupTp24Hr
Call lookupTp48Hr
Call lookupTp72Hr
Call lookupTp5Days
Call lookupwd24Hr
Call lookupwd48Hr
Call lookupwd72Hr
Call lookupwd5Days


Sheets("Hello World").Cells.ClearContents

fileNameBuoy1 = Dir()
  
Loop

When i want to open another file name which contain Buoy2, i added additional code 

Windows("hello world.xlsm").Activate
    Sheets("User Input").Select
    Dim FilePath As String, fileName As String
    FilePath = Cells(2, 2)
    fileNameBuoy1 = Dir(FilePath & "Buoy1*.xl??")
  fileNameBuoy2 = Dir(FilePath & "Buoy2*.xl??"
    Application.ScreenUpdating = False
    Application.DisplayAlerts = False
as well as a Do While loop with all the name changed from fileNameBuoy1 to fileNameBuoy 2

However it gives error at

fileNameBuoy1 = Dir()
it works perfectly for only filenameBuoy1. However it gives error once i added the Buoy 2 code. May I know why?Thanks!