Unable to find out reason of error Cross-thread operation not valid from C++ callback to C# -

i'm going implement mvc structure of delegate same in objective-c. functionality bluetooth device return me signal grab in c++ callback , signal message going forward callback of c# lambda function. got following error,

cross-thread operation not valid: control 'label1' accessed thread other thread created on.

my c# code form1.cs,

[unmanagedfunctionpointer(callingconvention.stdcall)]     delegate void progresscallback(char thevalue);  private void button1_click(object sender, eventargs e)         {              if (nclwrapper.isnclinitialized())                 {                     nclwrapper.callncldiscovery();                     label1.text = nclwrapper.getledpattern();                      progresscallback callback = (thevalue) =>                     {                       //crash here when going assign value lable.                         this.label1.text = thevalue.tostring();                         console.writeline("progress = {0}", thevalue);                     };                     nclwrapper.dowork(callback);                  }             }         } 

my c++ dll wrapper in c#

[dllimport("my.dll", callingconvention = callingconvention.cdecl, charset = charset.auto)]     public static extern void dowork([marshalas(unmanagedtype.functionptr)] progresscallback callbackpointer); 

my c++ .cpp class delegate assignment,

 progresscallback mydelegateobject;     __declspec(dllexport) void dowork(progresscallback progresscallback)     {             if (progresscallback)             {               mydelegateobject = progresscallback;             }     } 

my c++ sending callback message

void callback(myevent event, void* userdata){      wchar_t  ch[6];     ulong  ulsize;     switch(event.type){ /// [callbackinit]     case my_event_init:             if(event.init.success) gmyinitialized=true;             else exit(-1);             prevevent = event.type;              break; /// [callbackagreement]         case my_event_agreement:             ghandle=event.agreement.myhandle;             for(unsigned i=0; i<my_agreement_patterns; ++i){                 for(unsigned j=0; j<my_leds; ++j){                     if(event.agreement.leds[i][j]){                         ch[j]='1';                     }else{                         ch[j]='0';                     }                 }                 std::cout<<"\n";             }             ch[5]='\0';             ulsize = (wcslen(ch) * sizeof(wchar_t)) + sizeof(wchar_t);             ledpattern = null;             ledpattern = (wchar_t*)::cotaskmemalloc(ulsize);             wcscpy(ledpattern, ch);             prevevent = event.type;              //my delegate callback here             mydelegateobject('d');             break;          default: break;     }  } 

where i'm wrong?

 progresscallback callback = (thevalue) =>                     {                         label1.invoke((methodinvoker)delegate {                              label1.text = thevalue.tostring();                         });                     }; 

this code stuff update label text.