I can't be this dumb surely

OK, I am new to Basic4ppc, but I can make this work in other languages.

Select ComboBox18.SelectedIndex
Case 0,1,7 RiskVal=RiskVal + 1
Case 2,3,5,6 RiskVal=RiskVal + 2
Case 4 RiskVal=RiskVal + 5
Case else RiskVal=RiskVal + 0
End Select

I know I can use ComboBox.SelecttedIndex to update RiskVal as in

RiskVal=RiskVal + ComboBox3.SelectedIndex + 1

which works just fine, so what part of the syntax of the Case statement is illuding me, it just returns a 0 value.

You should write:
Select ComboBox18.SelectedIndex
Case 0,1,7
RiskVal=RiskVal + 1
Case 2,3,5,6
RiskVal=RiskVal + 2
Case 4
RiskVal=RiskVal + 5
Case else
RiskVal=RiskVal + 0
End Select

Doh!

Many thanks, I knew it had to be a simple syntax error but I hadn't tried that one.
I will bear it in mind in the future.