Option Button If Statements not working

Need message box to print out the BoilerRate value corresponding to what the user chooses on the Option Buttons, but it keeps printing out 0. What should I be dimming the buttons as? What am I missing?

This code is written under the OK Button private sub:

   If NatGas.Checked = True Then
        BoilerRate = 0.34
    ElseIf SixOil.Checked = True Then
        BoilerRate = 1.26
    ElseIf FourOil.Checked = True Then
        BoilerRate = 0.99
    ElseIf TwoOil.Checked = True Then
        BoilerRate = 0.48
    Else
        BoilerRate = 0.34
    End If
    MsgBox BoilerRate

Thank you!