I am new to VB6 and trying to create an application for my project using VB6. I am having 3 problems in the code during run-time:
1. If i press the calculate command button on my application i get a compile error: expected function or variable, when I call a sub procedure to another another sub procedure to input datas for numerical calculation.

2. It gives a second compile error: run-time error 6: Overflow with some of the equations (anodlife, totanodmass, maxgrdresist) as stated below

3. The third problem has to do with the link to the output form. If I press the calculate command button the output forms: frmcpcalculatedoutput, frmoffcalculatedoutput, will display :run-time error '91' : Object variable or with block variable not set. How can I link the output form to the mother form during compile time so that when I press the execute button on the child form it will cause the output to be displayed on the screen.

Below are snippets of the code. An urgent help will be appreciated. Thanks
'Gives me run-time error with the call subs. How do I get rid of it please
...
'Calculate sacrificial Anode mass
Sub sacranomass()
Call totcurreq
Dim totcurrequirement As Integer
totcurrequirement = totcurreq
Dim anodlife As Integer
Dim sacranomass As Integer
sacranomass = (anodlife * totcurrequirement) / (anodeweight * 49.3)
End Sub
Sub protareaanod()
Call totsurf
Call sacranomass
totalsurfacearea = totsurf
Dim protareaanod As Integer
protareaanod = totalsurfacearea / sacranomass
End Sub
....
'Gives me overflow problems. I declared my variables with integer. I tried long but won't end the over flow problem. When do I use Double to declare a numeric data type considering an output less than zero

'Calculation of anode life anodlife
Dim anodlife As Integer
anodlife = (anodeweight * energycapabilty * anoutizatfact) / (8760 * anoutputcurrent)

'Calculation of anode mass
Dim totanodmass As Integer
Dim totcurreq As Integer
Dim totcurrequirement As Integer
'Call totcurreq
totcurrequirement = totcurreq
totanodmass = (anodlife * totcurrequirement) / (anodeweight * 1000)

Dim maxgrdresist As Integer
maxgrdresist = (roh * anodeshapefactor) / ((anoquant) * anodelength) + (roh * parallelingfactor) / (anodespacing)

Thanks guys for helping out.

You can not assign a value to a Subroutine !!!
Define them as Function like : Private Function ABC As Integer

You are calling routine B in routine A and calling routine A in B !!!! that is why you are getting overflow

Why your code is like that ?? i think it it basically wrong , what you wanna do ??

tell me , all will write it for you

Got that figured out already mate. You can imagine how my code looks now.

The overflow problem was not actually due to the calling. It was due to the fact that some of the variables used in the equation were not assigned values and because i was using a sub instead of a function which would have assigned values were i needed them. So there is nothing wrong calling functions into other functions to return values for calculations.