Error while evaluating uicontrol Callback

here is the code where i have the error

function karaoke_btn_Callback(hObject, eventdata, handles)
% hObject    handle to karaoke_btn (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

set(handles.path_txt,'Enable','off');
set(handles.input_btn,'Enable','off');
set(handles.out_txt,'Enable','off');
set(handles.output_btn,'Enable','off');
set(handles.fc_slider,'Enable','off');
set(handles.hpcut_txt,'Enable','off');

file = get(handles.input_txt,'String');
try
  [y,Fs,nbits]= wavread(file);
catch
  msgbox('Invalid File');
  set(handles.path_txt,'Enable','on');
  set(handles.input_btn,'Enable','on');
  set(handles.out_txt,'Enable','on');
  set(handles.output_btn,'Enable','on');
  set(handles.fc_slider,'Enable','on');
  set(handles.hpcut_txt,'Enable','on');
  return;
end
%Remove Voice and save the file
left=y(:,1);
right=y(:,2);
karaoke_wav= wavwrite(left-right, fs,'ramright.wav');
%%%%%%%%%%%%%%%%%%
[p name ext] = fileparts(file);
dir = get(handles.out_txt,'String');
if isdir(dir)
  wavwrite(karaoke_wav,Fs,nbits,[dir '\' name ext]);
else
  wavwrite(karaoke_wav,Fs,nbits,[cd '\' name ext]);
end