System.MethodMissingException calling a code module

Hi all,

I have created a code module that has a class with static members that I call from server activities, and all has gone OK till I've added new methods to this class. Once I've distributed the new version, when I create a new flow that uses an old method from this class I get a System.MethodMissingException. What's going wrong? Any help would be appreciated.

Thanks

[EXCEPTION]
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.MissingMethodException: Method not found: 'ServiceDispatcher ProcessHelper.GetServiceDispatcher(SourceCode.KO.ServerEventContext, System.String, System.String, System.String)'.
at K2Code7252.Main(ServerEventContext K2)
--- 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 SourceCode.KO.ProcessInstance.ExecuteCode(Int32 codeid, State state, ContextType ctxt, Object ctxtobj, Int32 objid, String ctxtname, Int32 excepid)