Without any code provided, the only solution left for you is to:
- put a beakpoint at the beginning of the method handling the conversion.
- lauch your project in debug mode (F5 in Visual Studio).
- go on from line to line and watch carefully for the values of your variables ; you have to wonder what it is you expect for them, and what you actually get; the difference will point the problem.
Seeing your code, then Solution 2 by Original Griff is the one that does exactly what you want to do the way you want to do it, but without limitations.
I would just change the way you get your
value from your textBox:
If (Int32.TryParse(s1, i1))
s2 = Convert.ToString(i1, 8)