Problem with SetFocus

Hey everyone!

I am having a little trouble with an addition flash card userform that I am working on. Everything was working exactly as I intended until I tried to implement a keyup event. My intention was to remove the need to press return twice (once for entering answer in text box, and once again to proceed to the next question). Now, with the keyup event, I am able to enter the answer and go to the next question, however the focus is then placed on the "Next" command button. I have tried putting "me.txtSolution.SetFocus" throughout my code to no avail. Any thoughts would be greatly appreciated.

Thank you for your help! This is what I have so far:

Private Sub btnNext_Click()
    
    Dim n1, n2 As Integer
    
    If IsNumeric(txtSolution.Value) Then
        lblAddend1.ForeColor = vbBlack
        lblAddend2.ForeColor = vbBlack
    If Int(lblAddend1.Caption) + Int(lblAddend2.Caption) <> Int(txtSolution.Value) Then
        lblAddend1.ForeColor = vbRed
        lblAddend2.ForeColor = vbRed
        txtSolution.Value = ""
    Else
        txtSolution.Value = ""
        
        Dim high, low As Double
        
        low = Worksheets("Data").Range("C4").Value
        high = Worksheets("Data").Range("C5").Value
        low2 = Worksheets("Data").Range("F4").Value
        high2 = Worksheets("Data").Range("F5").Value
        n1 = Int((high - low + 1) * Rnd() + low)
        n2 = Int((high2 - low2 + 1) * Rnd() + low2)
        lblAddend1.Caption = n1
        lblAddend2.Caption = n2
      
    End If
    Else
        txtSolution.Value = ""
    End If
    Me.txtSolution.SetFocus
    
End Sub

Private Sub txtSolution_KeyDown(ByVal KeyCode As MSForms.ReturnInteger, ByVal Shift As Integer)
    
    If KeyCode = vbKeyReturn Then
        Call btnNext_Click
    End If

End Sub