Fix argument checking

Change-Id: I21c7c1ccba8130006b34fcfc913867368cf502f5
diff --git a/tools/test/bin/onos-validate-release b/tools/test/bin/onos-validate-release
index c9afc82..cae945d 100755
--- a/tools/test/bin/onos-validate-release
+++ b/tools/test/bin/onos-validate-release
@@ -8,7 +8,7 @@
 export ONOS_VERSION=$1
 RELEASE=$2
 
-[ -z "$ONOS_VERSION" -o -z "$ONOS_VERSION" ] && echo "usage: $(basename $0) <version> <release,nightly>" >&2 && exit 1
+[ -z "$ONOS_VERSION" -o -z "$RELEASE" ] && echo "usage: $(basename $0) <version> <release,nightly>" >&2 && exit 1
 
 DIR=$(mktemp -d /tmp/onos-test.XXXXX) &&
   echo "Created tempdir for release: $DIR" ||