fixed a typo

diff --git a/src/rrd.c b/src/rrd.c
index 24add69fc05abee55e28d74c1bfcc9b4f48d797b..fe264cf789db04be2608c0de323621f9bfbefc76 100755 (executable)
--- a/src/rrd.c
+++ b/src/rrd.c
@@ -978,7 +978,7 @@ unsigned long long rrdset_done(RRDSET *st)
                                        rd->last_collected_value = rd->collected_value;
                                }
 
-                               rd->calculated_value = (calculated_number)(rd->collected_value - rd->last_collected_value);
+                               rd->calculated_value += (calculated_number)(rd->collected_value - rd->last_collected_value);
 
                                if(unlikely(st->debug))
                                        debug(D_RRD_STATS, "%s/%s: CALC INC "