Problem with sqrt

Hi!
I have problem with sqrt.

Code is:

Option Explicit
Dim X As Range
Dim Y As Range
Dim XT As Variant
Dim XTX As Variant
Dim odw As Variant
Dim XTy As Variant
Dim a As Variant
Dim rowY As Long
Dim rowX As Long
Dim rowW As Long
Dim i As Long
Dim colY As Long
Dim nazwa As Variant
Dim colX As Long
Dim yte As Variant
Dim o As Variant
Dim m As Long
Dim ysr As Long
Dim R2 As Long
Dim war As Variant
Dim Su As Variant

Private Sub CommandButton1_Click()
    End
End Sub

Sub CommandButton2_Click()

    'pierwsze obliczenia
    
Set X = Range(RefEdit1)
Set Y = Range(RefEdit2)
XT = Application.WorksheetFunction.Transpose(X)
rowX = X.Rows.Count
rowY = Y.Rows.Count
colY = Y.Columns.Count
colX = X.Columns.Count
    
    'warunki
    
If colY > 1 Or colY < 1 Then
    MsgBox ("Liczba kolumn macierzy Y powinna wynosić 1")
End If
If rowX > rowY Or rowX < rowY Then
    MsgBox ("Liczba wierszy macierzy Y i X powinna być taka sama")
    End
End If

    'parametry
    
    XTX = Application.WorksheetFunction.MMult(XT, X)
    odw = Application.WorksheetFunction.MInverse(XTX)
    XTy = Application.WorksheetFunction.MMult(XT, Y)
    a = Application.WorksheetFunction.MMult(odw, XTy)
    yte = Application.WorksheetFunction.Transpose(Application.WorksheetFunction.MMult(Application.WorksheetFunction.Transpose(a), XT))
    ysr = Application.WorksheetFunction.Average(Y)
    
    'R2
    
    ReDim diff(1 To rowY, 1 To colY)
    
    For m = 1 To rowY
         diff(m, 1) = ((Y(m, 1) - yte(m, 1)) ^ 2)
    Next m

    ReDim diff2(1 To rowY, 1 To colY)
    
    For m = 1 To rowY
         diff2(m, 1) = (Y(m, 1) - ysr) ^ 2
    Next m

    o = Application.WorksheetFunction.Sum(diff) / Application.WorksheetFunction.Sum(diff2)
    R2 = 1 - o
    
    'Odchylenie
    
    war = Application.WorksheetFunction.Sum(diff) / (rowX - colX)
    Su = war^(1 / 2)
    
           'Wyniki

Sheets.Add
ActiveSheet.Name = "Wyniki KMNK"
Range("A1").Value = "Parametry: "
Range(Cells(2, 1), Cells(colX + 1, 1)).Select
Selection.Value = a
Range("C1").Value = "Y^"
Range(Cells(2, 3), Cells(colY + 1, 3)).Select
Selection.Value = yte
Range("F1").Value = "R2: współczynnik determinacji"
Range("H1").Value = R2
Range("F2").Value = "Su: odchylenie standardowe"
Range("H2").Value = Su
End Sub

Error: Type declaration character does not much declared data type.

It is about war variable.

Please help