play wav file error

when i open a wav file and push play button, it has do nothing. In timer it shows 0.0233107 and when i push stop button, it shows 9.07029e-05. But there is no sound. In axes it plot a signal, i hope it is true.

 function Play_Callback(hObject, eventdata, handles)
global pl;
global c;
global t;
global sf;
play(pl);
if isplaying(pl)
    pause(pl);
    set(handles.Play,'string','Play');
else
    resume(pl);
    set(handles.Play,'string','Pause');
end
c=get(pl,'Currentsample');
t=get(pl,'Totalsample');
global mydata;
mydata=guidata(handles.text1);
a=timer;
set(a,'executionMode','fixedRate');
set(a,'TimerFcn','myfunction','Period',0.1);
start(a);