Require a directory that could actually exist.

Change-Id: I6030a062dc9f6a40ea32ecbb612c2b9353fc1af6
diff --git a/core/tasks/cts.mk b/core/tasks/cts.mk
index 17a7a0e..46c168b 100644
--- a/core/tasks/cts.mk
+++ b/core/tasks/cts.mk
@@ -91,7 +91,7 @@
 	$(CTS_CORE_CASE_LIST) \
 	$(CTS_SECURITY_APPS_LIST)
 
-DEFAULT_TEST_PLAN := $(PRIVATE_DIR)/resource/plans
+DEFAULT_TEST_PLAN := $(cts_dir)/$(cts_name)/resource/plans
 
 $(cts_dir)/all_cts_files_stamp: PRIVATE_JUNIT_HOST_JAR := $(junit_host_jar)