Problem deleting registery values with its subkeys

Private Sub Command3_Click()
    'Delete the setting from the registry
    DelSetting HKEY_CURRENT_USER, "KPD-Team", "BinaryValue"
    MsgBox "The value was deleted ...", vbInformation + vbOKOnly, App.Title
End Sub

Private Sub Command2_Click()
    'Delete the setting from the registry
    DelSetting HKEY_CURRENT_USER, "Software\xyz\foldername\"
    MsgBox "The value was deleted ...", vbInformation + vbOKOnly, App.Title

End Sub

Compile error:

Argument not optional 

'This program needs 3 buttons
Const REG_SZ = 1 ' Unicode nul terminated string
Const REG_BINARY = 3 ' Free form binary
Const HKEY_CURRENT_USER = &H80000001
Private Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long
Private Declare Function RegCreateKey Lib "advapi32.dll" Alias "RegCreateKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Private Declare Function RegDeleteValue Lib "advapi32.dll" Alias "RegDeleteValueA" (ByVal hKey As Long, ByVal lpValueName As String) As Long
Private Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Private Declare Function RegQueryValueEx Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, lpData As Any, lpcbData As Long) As Long
Private Declare Function RegSetValueEx Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, lpData As Any, ByVal cbData As Long) As Long
Function RegQueryStringValue(ByVal hKey As Long, ByVal strValueName As String) As String
    Dim lResult As Long, lValueType As Long, strBuf As String, lDataBufSize As Long
    'retrieve nformation about the key
    lResult = RegQueryValueEx(hKey, strValueName, 0, lValueType, ByVal 0, lDataBufSize)
    If lResult = 0 Then
        If lValueType = REG_SZ Then
            'Create a buffer
            strBuf = String(lDataBufSize, Chr$(0))
            'retrieve the key's content
            lResult = RegQueryValueEx(hKey, strValueName, 0, 0, ByVal strBuf, lDataBufSize)
            If lResult = 0 Then
                'Remove the unnecessary chr$(0)'s
                RegQueryStringValue = Left$(strBuf, InStr(1, strBuf, Chr$(0)) - 1)
            End If
        ElseIf lValueType = REG_BINARY Then
            Dim strData As Integer
            'retrieve the key's value
            lResult = RegQueryValueEx(hKey, strValueName, 0, 0, strData, lDataBufSize)
            If lResult = 0 Then
                RegQueryStringValue = strData
            End If
        End If
    End If
End Function
Function GetString(hKey As Long, strPath As String, strValue As String)
    Dim Ret
    'Open the key
    RegOpenKey hKey, strPath, Ret
    'Get the key's content
    GetString = RegQueryStringValue(Ret, strValue)
    'Close the key
    RegCloseKey Ret
End Function
Sub SaveString(hKey As Long, strPath As String, strValue As String, strData As String)
    Dim Ret
    'Create a new key
    RegCreateKey hKey, strPath, Ret
    'Save a string to the key
    RegSetValueEx Ret, strValue, 0, REG_SZ, ByVal strData, Len(strData)
    'close the key
    RegCloseKey Ret
End Sub
Sub SaveStringLong(hKey As Long, strPath As String, strValue As String, strData As String)
    Dim Ret
    'Create a new key
    RegCreateKey hKey, strPath, Ret
    'Set the key's value
    RegSetValueEx Ret, strValue, 0, REG_BINARY, CByte(strData), 4
    'close the key
    RegCloseKey Ret
End Sub
Sub DelSetting(hKey As Long, strPath As String, strValue As String)
    Dim Ret
    'Create a new key
    RegCreateKey hKey, strPath, Ret
    'Delete the key's value
    RegDeleteValue Ret, strValue
    'close the key
    RegCloseKey Ret
End Sub
Private Sub Command1_Click()
    Dim strString As String
    'Ask for a value
    strString = InputBox("Please enter a value between 0 and 255 to be saved as a binary value in the registry.", App.Title)
    If strString = "" Or Val(strString) > 255 Or Val(strString) < 0 Then
        MsgBox "Invalid value entered ...", vbExclamation + vbOKOnly, App.Title
        Exit Sub
    End If
    'Save the value to the registry
    SaveStringLong HKEY_CURRENT_USER, "KPD-Team", "BinaryValue", CByte(strString)
End Sub
Private Sub Command2_Click()
    'Get a string from the registry
    Ret = GetString(HKEY_CURRENT_USER, "KPD-Team", "BinaryValue")
    If Ret = "" Then MsgBox "No value found !", vbExclamation + vbOKOnly, App.Title: Exit Sub
    MsgBox "The value is " + Ret, vbOKOnly + vbInformation, App.Title
End Sub
Private Sub Command3_Click()
    'Delete the setting from the registry
    DelSetting HKEY_CURRENT_USER, "KPD-Team", "BinaryValue"
    MsgBox "The value was deleted ...", vbInformation + vbOKOnly, App.Title
End Sub
Private Sub Form_Load()
    'KPD-Team 1998
    'URL: http://www.allapi.net/
    'E-Mail: KPDTeam@Allapi.net
    Command1.Caption = "Set Value"
    Command2.Caption = "Get Value"
    Command3.Caption = "Delete Value"
End Sub

Private Sub Command3_Click()
    'Delete the setting from the registry
    DelSetting HKEY_CURRENT_USER, "Software\xyz\", "FolderName"
    MsgBox "The value was deleted ...", vbInformation + vbOKOnly, App.Title
End Sub