GUI Pop-up menu problem with the text in the "String"

When I run the GUI which contains popupmenu with "Text" in the "String" property of the popupmenu, I got the following problems:

1) I cannot access the window from "guide" anymore !!

2) I got the following error mesage:

Warning: 'popupmenu' control requires a non-empty Character vector

Control will not be rendered until all of its parameter values are valid

> In matlab.hg.internal.openfigLegacy (line 128)

In gui_mainfcn>local_openfig (line 286)

In gui_mainfcn (line 233)

In Boundry_Inormation (line 42)

• I use the following: "dbstop if warning", but its not help
• I use this: set(handles.popupmenu5, 'string', str); but not work as well

Please, help