typo/bug found by Christian Glahn Daniel

* valid.c: typo/bug found by Christian Glahn
Daniel
diff --git a/valid.c b/valid.c
index 58ab756..196ea2b 100644
--- a/valid.c
+++ b/valid.c
@@ -4837,7 +4837,7 @@
     int ret = 1;
     xmlNodePtr cur, child;
 
-    if ((ctxt == NULL) || (doc == NULL) | (elem == NULL))
+    if ((ctxt == NULL) || (doc == NULL) || (elem == NULL))
 	return(0);
 
     child = elem->children;