flex button multiply clicks -

in project (mp3 player) when click button 'play' starts amd plays normal, when click button 'next song' multiplys clicks,(2 clicks multiply 2 times, 3 clicks 3 times...) , it's starting 2 or 3 or more songs in background. why it's multiply button clicks? can me?

buttons:

<s:button id="playbtn" x="97" y="14" width="79" height="24" label="play"            click="playbutton_clickhandler(event)" enabled="true"/> <s:button id="nastepnybtn" x="354" y="14" width="79" height="24" label="=&gt;&gt;" click="nastepnybtn_clickhandler(event)"/> 

actions:

  protected function playbutton_clickhandler(event:mouseevent):void {odtwarzaj();}    protected function nastepnybtn_clickhandler(event:mouseevent):void {odtwarzaj(1);} 

playcode:

   function odtwarzaj(tryb:number=0):void{             var wybrany:object = datagridid.selecteditem;              if(wybrany!=null){                 switch(tryb){                     case 0:                         if(playing)                         stop();                          wybranykawalek=datagridid.selectedindex;                         break;                     case 1:                         if(!normalnie.selected){                             alert.show("losuje");                         }else                         {                             if(wybranykawalek==tablica.length-1){                                 wybranykawalek=0;                             }else                             {                                 wybranykawalek=wybranykawalek+1;                             }                          }                         stop();                         //playing=false;                         break;                     case 2:                         if(!normalnie.selected){                             alert.show("losuje");                           }else                         {                             if(wybranykawalek==0){                                 wybranykawalek=tablica.length-1;                             }                             else{                                     wybranykawalek=wybranykawalek-1;                             }                         }                         stop();                         //playing=false;                         break;                      }                       alert.show("test="+test+" tryb="+tryb+" wybrany:"+wybranykawalek+" t.l="+tablica.length+" dg.si="+datagridid.selectedindex);                       playinglable.text=tablica.getitemat(wybranykawalek).artysta+" - "+tablica.getitemat(wybranykawalek).tytul;                     file = new file(tablica.getitemat(wybranykawalek).url_pliku);                      if(!playing){                         muzyka=new sound();                         muzyka.addeventlistener(ioerrorevent.io_error, errorhandlermusic);                         muzyka.addeventlistener(event.complete, loadcompletemusic);                         muzyka.load(new urlrequest(file.url));//, context                          }               }else{                 alert.show("zaznacz plik odegrania!");             }              test++;         } 

playstart function:

      private function play(pos:number=0):void{             playing=true;             kanal=muzyka.play(pos,trans);             refresh();             addeventlistener(event.enter_frame, displayprogressinsec);         } 

the problem here calling addeventlistener(event.enter_frame, displayprogressinsec) everytime hit button never removing it. everytime add listener, accumulates , responds enter-frame event.