How to check minimum aperture for gap width?

Hi All !
  This is my exmaple code that will check "minimum aperture fo gap width" but not work, so i post here hoping receive advices to fix it.
   ( Get void ==> create shape from void ==> check shape minimum aperture with 70um ==> next void check)
    Here my ex code:

axlCmdRegister("shp_chk" `shp_chk)
(defun shp_chk ()
    AllVoidsInDesign = list()
    axlSetFindFilter(?enabled '(noall VOIDS) ?onButtons '(noall VOIDS))
    axlClearSelSet()
    mypopup = axlUIPopupDefine( nil
    (list (list "Done" 'axlFinishEnterFun)
    (list "Cancel" 'axlCancelEnterFun)))
    axlUIPopupSet( mypopup)
    AllVoidsInDesign = axlGetSelSet(axlSelect(?prompt "Select a void..."))
    axlClearSelSet()
    
    if(length(AllVoidsInDesign)== 0 then
        axlUIConfirm("No Void selected. ")
    else
        foreach(void AllVoidsInDesign
            void_poly = car(axlPolyFromDB(void))
            shape_ID = car(axlDBCreateShape(void_poly,t,"ETCH/25PA",nil,nil))
            shape_center = axlDBAltOrigin('center shape_ID)
            cmd_str = sprintf(nil "shape check; pick %.2f %.2f; fillin %L", xCoord(shape_center), yCoord(shape_center), "70")
            axlShell(cmd_str)
            axlShell("Done")
        );end foreach
    );end if
);end defun shp_chk