need to convert time to minutes in userform

I know how to do this in a worksheet:

=(b1-a1)*1440

B1 being the end time and A1 being the start time

I have a userform where the start time and end time are entered in text boxes

txtstart1 and txtend1

I would like the result to show up in txtmin1

Here is my code that doesnt work. I tried to convert code from a non-time sheet of mine. Dim as Integer may be the problem, I just learn as I go, and so far have only dealt with Integers.

Private Sub txtend1_Exit(ByVal Cancel As MSForms.ReturnBoolean)

Dim endnum1 As Integer, startnum1 As Integer

    With frmquota
    
    If txtend1.Value = "" Then
        endnum1 = 0
    Else
        endnum1 = txtend1.Value
    End If
    
        If txtstart1.Value = "" Then
        startnum1 = 0
    Else
        startnum1 = txtstart1.Value
    End If
    
    txtmin1.Value = endnum1 - startnum1 * 1440
    
    End With
    
End Sub

Thank you for any help