diff --git a/mg/create_dwa.csh b/mg/create_dwa.csh
index 281e612..38de63f 100644
--- a/mg/create_dwa.csh
+++ b/mg/create_dwa.csh
@@ -5,16 +5,23 @@ if ( $1 == '' ) then
     exit
 endif
 
+
+if ( $2 == '' ) then
+    echo 'VCO is not specified.'
+    exit
+endif
+
+if ( $2 != 'aoi' && $2 != 'aoi-dbg' ) then
+    echo 'VCO is unknown.'
+    exit
+endif
+
+set VVCO=$2
+
 mkdir -p $1
 cd $1
 setenv DWA `pwd`
 
-if ( $2 != '' ) then
-    set VVCO=$VCO-$2
-else
-    set VVCO=$VCO
-endif
-
 ic_dwa -lv $IWA $DWA $VVCO
 
 ######################