Time [type mismatch]

[Neisany]

Trying to subtract the end time from the start time and display it in an empty cell that I provided early on. I would like the number displayed in number of hours IE 1.5 Hours. but if not possible I can manage with 1:30 hours.

With the code below I get
rune time error 13
type mismatch

Private Sub txtstart__LostFocus()
    TxtStart.Text = format(TxtStart.Text, "hh:mm:ss")
    
End Sub
Private Sub txtend__LostFocus()
    txtend.Text = format(txtend.Text, "hh:mm:ss")
    
End Sub
Private Sub UpdateButten1_click()
 ............         
        .Cells(emptyrow, 5).Value = txtend.Value - TxtStart.Value
.........
end sub