System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.FormatException: Input string was not in a correct format.
   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
   at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
   at System.Int32.Parse(String s)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
   at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)
   at System.Type.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args)
   at fitnesse.mtee.engine.MethodMember.Invoke(Object instance, Object[] parameters)
   at fitnesse.mtee.operators.DefaultParse.Parse(Processor processor, State state)
   at fitnesse.mtee.engine.Processor.Parse(Type type, Tree`1 input)
   at fitnesse.handlers.AbstractCellHandler.Parse(Fixture theFixture, Parse theCell, Type theType, Object theTarget)
   at fitnesse.handlers.AbstractCellHandler.HandleInput(Fixture fixture, Parse cell, Accessor accessor)
   at fit.Parse.Value(Fixture theFixture, Type theType)
   at fitlibrary.DefaultHandler.HandleEvaluate(Fixture theFixture, Parse theExpectedValueCell, Accessor theAccessor)
   at fitnesse.handlers.AbstractCellHandler.HandleCheck(Fixture fixture, Parse cell, Accessor accessor)
   at fitlibrary.FlowFixtureBase.Check(Parse theCells)