diff --git a/bin/check.sh b/bin/check.sh
index a9db4209..759f236a 100755
--- a/bin/check.sh
+++ b/bin/check.sh
@@ -103,7 +103,7 @@ function run_sipp
     ${BIN_DIR}/sipp.sh -d ${DOMAIN} -p ${PORT} -m ${MPORT} -r ${SCEN_CHECK_DIR}/${base}.xml &
     responder_pid="${responder_pid} ${base}:$!:${PORT}:${MPORT}"
     let PORT=${PORT}+1
-    let MPORT=${MPORT}+2
+    let MPORT=${MPORT}+3
   done
   status=0
   # let's fire sipp scenarios
@@ -192,6 +192,12 @@ if [ "${PROFILE}" != "CE" ] && [ "${PROFILE}" != "PRO" ]; then
   exit 2
 fi
 
+if [ ! -d ${SCEN_CHECK_DIR} ]; then
+  echo "no ${SCEN_CHECK_DIR} found"
+  usage
+  exit 3
+fi
+
 if [ -z $SKIP ]; then
   delete_voip ${DOMAIN} # just to be sure nothing is there
   create_voip ${DOMAIN}