Disabling comboboxes after a certain limit has been met

Question

I have 4 comboboxes called:
cboOption1 
cboOption2 
cboOption3 
cboOption4
Each of them can have one of 2 values, either 10 or 20 points, which the user selects from a drop down. However, the user can only select a maximum of 40 points across all drop downs, after which the remaining dropdowns that follow will be disabled.
E.g. 1
cboOption1 = 20
cboOption2 = 20
Then
cboOption3.Enabled = False
cboOption3.Enabled = False 
E.g. 2
cboOption1 = 10
cboOption2 = 20
cboOption3 = 10
Then
cboOption4.Enabled = False 
E.g. 3
cboOption1 = 10
cboOption2 = 10
cboOption3 = 10
cboOption3 = 40
Then
None disabled.
My problem
The difficulty I'm experiencing at the moment is figuring out how to flick the comboboxes on/off in response to user input. This is my code so far, it doesn't seem to be working too well, any idea how I can improve it.
Code so far
Sub checkTotal(var1, var2, var3, var4, total)
so1 = Int(var1)
so2 = Int(var2)
so3 = Int(var3)
so4 = Int(var4)
total = Nz(so1, 0) + Nz(so2, 0) + Nz(so3, 0) + Nz(so4, 0)
If total > 40 And (so1 = "20" Or so2 = "20" Or so3 = "20" Or so4 = "20") Then
cboOption3.Value = ""
cboOption3.Enabled = False
cboOption4.Value = ""
cboOption4.Enabled = False
End If
MsgBox total
End Sub
Private Sub cboOption1_Change()
Call checkTotal(cboOption1.Column(1), cboOption2.Column(1), cboOption3.Column(1), cboOption4.Column(1), so1RunningTotal)
End Sub
Private Sub cboOption2_Change()
Call checkTotal(cboOption1.Column(1), cboOption2.Column(1), cboOption3.Column(1), cboOption4.Column(1), so1RunningTotal)
End Sub
Private Sub cboOption3_Change()
Call checkTotal(cboOption1.Column(1), cboOption2.Column(1), cboOption3.Column(1), cboOption4.Column(1), so1RunningTotal)
End Sub
Private Sub cboOption4_Change()
Call checkTotal(cboOption1.Column(1), cboOption2.Column(1), cboOption3.Column(1), cboOption4.Column(1), so1RunningTotal)
End Sub

Answer 1

Hi Methuselah,
You are using VB6, it is antique, that while it needs a license to use and to deploy programs from.
There is currently at Microsoft a complete community 2013 version of the latest version of VB (VB12 also named VB2013), why not try that one.
You can use it free and deploy the programs you've made with it.
http://www.visualstudio.com/en-us/downloads/download-visual-studio-vs.aspx
It is bellow the 90 day versions and then the community one.
Success
Cor