feeds not update exist node and only add them I am using feeds module in order to import node from csv file,
The mapping equation is 


and the updating criteria set to 


and my csv file contain this

guid,field_type,field_model,field_cost,
1,type1,model1,cost300,
2,type1,model2,cost300,
3,type1,model3,cost300,
4,type1,model4,cost400,
5,type1,model5,cost5,
6,type6,model6,cost6,
7,type7,model7,cost7,
8,type8,model8,cost8,
9,type9,model9,cost9,
10,type10,model10,cost10,


my problem is every time i import csv file the recorded added to my node (not update or replace), where is the problem?
The problem is here NOT UNIQUE field set.after set a field as a unique field every time the nodes will update(replaced).
To  set a field as unique click a button below not set as unique , check unique checkbox and update then it will set as unique.