Index: trunk/ippTools/src/stacktool.c
===================================================================
--- trunk/ippTools/src/stacktool.c	(revision 16724)
+++ trunk/ippTools/src/stacktool.c	(revision 16726)
@@ -99,10 +99,5 @@
     PXOPT_LOOKUP_STR(workdir, config->args, "-workdir", true, false);
 
-    // default
-    PXOPT_LOOKUP_BOOL(simple, config->args, "-simple", false);
-    PXOPT_LOOKUP_TIME(registered, config->args, "-registered", false, false);
-
     psMetadata *where = psMetadataAlloc();
-    PXOPT_COPY_STR(config->args, where, "-select_exp_type", "exp_type", "==");
     // map -inst -> camera
     PXOPT_COPY_STR(config->args, where, "-select_inst", "camera", "==");
@@ -126,6 +121,12 @@
     if (!psListLength(where->list)) {
         psFree(where);
-        where = NULL;
-    }
+        psError(PXTOOLS_ERR_DATA, false, "search parameters are required");
+        return false;
+    }
+
+    // default
+    PXOPT_LOOKUP_BOOL(simple, config->args, "-simple", false);
+    PXOPT_LOOKUP_TIME(registered, config->args, "-registered", false, false);
+    PXOPT_COPY_STR(config->args, where, "-select_exp_type", "exp_type", "==");
 
     psString query = pxDataGet("stacktool_find_complete_warps.sql");