diff --git a/README.md b/README.md
index ed82cd5b2a..08ea0417e7 100644
--- a/README.md
+++ b/README.md
@@ -525,6 +525,9 @@ Response
 
 ```
 
+Please Note:
+_fields in Chart API can only take on numeric column as its argument.  
+
 
 ## Run dynamic queries
 Dynamic queries on a database can be run by POST method to URL localhost:3000/dynamic