How to use option group (checkbox) to change calculation in textbox

[neelsfer]

I have an option group with 2 checkboxes :
MtbAge - option value = 1
RoadAge - option value = 2

The textbox where to display MtbAge/RoadAge is called = currentage

if you select MtbAge it must use

=Format(DateSerial(Year(Date()),12,31)-[Birthdate],'yy')

to calculate

if you select RoadAge it must use

=DateDiff("yyyy",[Birthdate],Now())+Int(Format(Now(),"mmdd")<Format([Birthdate],"mmdd"))

to calculate

Anybody out there that has an idea how to do this please? See attached screen pic

** Edit **
[imgnothumb]http://bytes.com/attachments/attachment/4513d1294394815/checkbox1.jpg[/imgnothumb]

[Andrew Hulting]

I would try. I havent tested it, but

chkBox1 = MtbAge - option value = 1
chkBox2 = RoadAge - option value = 2

 If Forms![Main]![chkBox1] = true then textbox=Format(DateSerial(Year(Date()),12,31)-[Birthdate],"yy") 
If Forms![Main]![chkBox2]= true textbox=DateDiff("yyyy",[Birthdate],Now())+Int(Format(Now(),"mmdd")<Format([Birthdate],"mmdd"))

[neelsfer]

I tried the above, but could not get it to work.
i am attaching the file. Open race entries.
As you click on mtb age or road age, it must change the current age textbox in yellow. i also added the 2 formulas to the form to be used.
thx

[Andrew Hulting]

The -1 is whatever the value is when it is checked, I am working on an extreamly gimped PC right now, as I am havign major issues with dll's being courupt, and not being able to runa any code.

The premis is that when the condition of the checkbox being selected, than the age text box will use the appropriate formula.

If Forms![CyclistF]![MtbAge] = -1 Then Forms![CyclistF]![currentage] = Format(DateSerial(Year(Date), 12, 31) - [BirthDate], "yy")

If Forms![CyclistF]![RoadAge] = -1 Then Forms![CyclistF]![currentage] = DateDiff("yyyy", [BirthDate], Now()) + Int(Format(Now(), "mmdd") < Format([BirthDate], "mmdd"))

[neelsfer]

thx Andrew
I got it working through your help. Acalc is the overall name off the option group. I changed the values it produce, to 1 and 2

Private Sub Acalc_Click()
  If Forms![CyclistF]![Acalc] = 1 Then Forms![CyclistF]![currentage] = Format(DateSerial(Year(Date), 12, 31) - [BirthDate], "yy")
   
    If Forms![CyclistF]![Acalc] = 2 Then Forms![CyclistF]![currentage] = DateDiff("yyyy", [BirthDate], Now()) + Int(Format(Now(), "mmdd") < Format([BirthDate], "mmdd"))
End Sub