Pull operation works only on one array even called twice over a document

Over this document

{ "_id" : 1, "array1" : [ "sid", "yd" ], "array2" : [ "ram", "kp" ] }

I have run following query

db.getCollection('sid').update({_id:1},{$pull:

{array1:"sid"}

,$pull:{array2:"kp"}})

result:

{ "_id" : 1, "array1" : [ "sid", "yd" ], "array2" : [ "ram" ] }