Recursion is not reliable

Description

Recursion in the debugger is fine. After creating an application it is NOT. The example below generates an "outside of collection bounds"-error.

Example code to demonstrate the bug.

    pol$="*(/(v(x),v(x)),v(x))"
    print "here it is: ";maakVeeltermUitPolish$(pol$)
    wait

function maakVeeltermUitPolish$(pol$)
    print "IN pol$=["+pol$+"]"
    c1$=left$(pol$,1)

    select case c1$
        case "/","*"
            dummy = getArgUitPolish(pol$,argpol1$,argpol2$)
            arg1$ = maakVeeltermUitPolish$(argpol1$)
            arg2$ = maakVeeltermUitPolish$(argpol2$)
            maakVeeltermUitPolish$ = arg1$ + " "+c1$+" "+arg2$
        case "v"
            dummy = getArgUitPolish(pol$,argpol1$,argpol2$)
            maakVeeltermUitPolish$ = argpol1$
    end select

    print "UIT pol$=["+pol$+"] met "+maakVeeltermUitPolish$
end function

function getArgUitPolish(pol$, byref arg1pol$,byref arg2pol$)
    c1$=mid$(pol$,1,1)

    select case c1$
        case "/"
            arg1pol$ = "v(x)"
            arg2pol$ = "v(x)"
        case "*"
            arg1pol$ = "/(v(x),v(x))"
            arg2pol$ = "v(x)"
        case "v"
            arg1pol$ = "x"
            arg2pol$ = ""
    end select
end function

Example code to work around the bug.

'code to work around the bug goes here