DO NOT TRUST in what you see when step into a RELEASE build!
Because of code optimization, wrong values may be shown.
If you want to trace code also in RELEASE, use a logging system (e.g. write values in a log file) or call OutputDebugString function then look into Output window.
Anyway, turning off the compiler optimization in RELEASE is NOT a good solution.

One additional note: if use OutputDebugString, you can also trace the values in Sysinternals DebugView utility without being necessary to run your application from Visual Studio IDE.