Oracle Form freezes after configure WEBUTIL

I am using oracle forms 10g. It is web based oracle form application. I want to generate Excel Report from Oracle Forms 10g. I configured WEBUTIL and use CLIENT_OLE2 package. Procedure declared in trigger WHEN-BUTTON-PRESSED. When button pressed then suddenly the form freezes and they cannot do anything. Exit button and menu options stops working. It does not give any message and does not do any action also.

Procedure Code:

declare
 application client_ole2.obj_type;
 workbooks client_ole2.obj_type;
 workbook client_ole2.obj_type;
 worksheets client_ole2.obj_type;
 worksheet client_ole2.obj_type;
 cell client_ole2.obj_type;
 arglist client_ole2.list_type;
 row_num number;
 col_num number;
 fontObj client_ole2.obj_type;

cursor rec is SELECT so.descr saleorgdescr,ih.invdate invdatemaster, ih.docNUM docnum,
   TO_CHAR(ih.invdate,'mon-yyyy') invmonth
FROM ARMINVHEAD ih, SDMSALEORG so
WHERE
ih.status='69'
AND  TO_DATE(ih.INVDATE,'DD-MM-RRRR')
BETWEEN
                   TO_DATE('01-01-2008','DD-MM-RRRR') 
              AND  
                   TO_DATE('01-01-2009','DD-MM-RRRR')
order by IH.INVDATE, ih.docnum;

procedure SetCellValue(rowid number,colid number,cellValue varchar) is
 begin
 arglist := client_ole2.create_arglist;
 client_ole2.add_arg(arglist,rowid);
 client_ole2.add_arg(arglist,colid);
 cell:= client_ole2.get_obj_property(worksheet,'Cells',arglist);
 fontObj := client_ole2.get_obj_property(cell,'Font');
 client_ole2.destroy_arglist(arglist);
 client_ole2.set_property(cell,'value',cellValue);
 client_ole2.set_property(fontObj,'Size',16);
 client_ole2.set_property(fontObj,'BOLD',1);
 client_ole2.set_property(fontObj,'ColorIndex',7);
 client_ole2.release_obj(cell);
end SetCellValue;

procedure app_init is
 begin
 application := client_ole2.create_obj('Excel.Application');
 client_ole2.set_property(application,'Visible',true);
 workbooks := client_ole2.get_obj_property(application,'workbooks');
 workbook := client_ole2.Get_Obj_Property(workbooks,'add');
 worksheets := client_ole2.get_obj_property(application,'worksheets');
 worksheet := client_ole2.Get_Obj_Property(worksheets,'add');
 client_ole2.set_property(worksheet,'Name','Emp Sheet');
end app_init;

procedure save_excel(path varchar,filename varchar) is
 begin
 client_OLE2.Release_Obj(worksheet);
 client_OLE2.Release_Obj(worksheets);
 -- Save the Excel file created
 If path is not null then
   Arglist := client_OLE2.Create_Arglist;
   client_OLE2.Add_Arg(Arglist,path||'\'||file_name||'.xls');
   client_OLE2.Invoke(workbook, 'SaveAs', Arglist);
   client_OLE2.Destroy_Arglist(Arglist);
end if;
end save_excel;

begin
 app_init;
 row_num:=1;
 col_num:=1;
 SetCellValue(row_num,col_num,'saleorgdescr');
 col_num:=col_num + 1;
 SetCellValue(row_num,col_num,'invdatemaster');
 col_num:=col_num + 1;
 SetCellValue(row_num,col_num,'docnum');
 col_num:=col_num + 1;
 SetCellValue(row_num,col_num,'invmonth');
 for i in rec loop
 row_num:=row_num + 1;
 col_num:=1;
 SetCellValue(row_num,col_num,i.saleorgdescr);    
 col_num:=2;
 SetCellValue(row_num,col_num,i.invdatemaster);    
 col_num:=3;
 SetCellValue(row_num,col_num,i.docnum);
 col_num:=4;
 SetCellValue(row_num,col_num,i.invmonth);   
end loop;    
save_excel('C:','emp_data');       
client_OLE2.Release_Obj(workbook);
client_OLE2.Release_Obj(workbooks);
client_OLE2.Release_Obj(application);
end;

Most probably you're missing the files listed in one of the following two groups :

frmwebutil.jar, jacob.jar( perhaps frmall_jinit.jar also ) files in the \forms\java directory

or

jacob-1.14.3-x86.dll, JNIsharedstubs.dll and d2kwut60.dll files in the C:\Program Files (x86)\Java\jre1.8.0_xxx\bin directory

assuming your Oracle Fusion Middleware Home is C:\ORACLE_10g. If they do not exist in that directory, it's enough to move them there manually.

Moreover, they are preferred to be included in the CLASSPATH as CLASSPATH=C:\ORACLE_10g\forms\java\jacob.jar;C:\ORACLE_10g\forms\java\frmwebutil.jar;

and

Edit file C:\Program Files (x86)\Java\jre1.8.0_xxx\lib\security\java.policy as adding
permission java.security.AllPermission; to the bottom of the file
just before the last curly brace with a semi-colon };