MATLAB: What caused GUI problem after Push Button is pressed and any recommended solution

gui_mainfcn at 96gui_mainfcn(gui_statematlab gui

Hi. I have a GUI problem.
Here is code for the Push Button.
function runButton_Callback(hObject, eventdata, handles)
% selects graph1 as the current axes, so that
% Matlab knows where to plot the data
axes(handles.graph1)
range_find(pt, tau, fr, time_ti, gt, gr, freq, ...
 sigma, te, nf, loss, snro, range, out_option);
guidata(hObject, handles); % updates the handles
This is the code for the edit text for Pt
function ptEdit_Callback(hObject, eventdata, handles)
pt = str2num(get(hObject,'String'));
% checks to see if input is empty. if so, default input1_editText to 100
if (isempty(pt))
   set(hObject,'String','100')
   pt = str2num(get(hObject,'String'));
   msgbox('Please enter number only')
end
guidata(hObject, handles);
function ptEdit_CreateFcn(hObject, eventdata, handles)
% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
  set(hObject,'BackgroundColor','white');
end
When I run the GUI, I have the following error message ??? Undefined function or variable 'pt'.
Error in ==> mark_v1>runButton_Callback at 86 range_find(pt, tau, fr, time_ti, gt, gr, freq, …
Error in ==> gui_mainfcn at 96 feval(varargin{:});
Error in ==> mark_v1 at 42 gui_mainfcn(gui_State, varargin{:});
Error in ==> @(hObject,eventdata)mark_v1('runButton_Callback',hObject,eventdata,guidata(hObject))
??? Error while evaluating uicontrol Callback
What can I do to overcome this problem? Any advice regarding this matter is highly appreciated. Thanks.
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