Extjs4 grid's paging functionality is not working - grid

Question

i am working in extjs4. I am adding paging functionality to grid. I am having my grid view code as-
allQuestionPapers.js
Ext.define('Balaee.view.qb.qbqns. ', {
extend : 'Ext.grid.Panel',
alias : 'widget.paperlist',
id : 'paperId',
store : 'qb.QbqnsStore',
border : false,
// height:autoheight,
width : 600,
autoScroll : true,
columns : [{
text : 'date',
width : 200,
dataIndex : 'createDate'
}, {
text : 'QuestionpaperNo',
width : 200,
dataIndex : 'questionPaperNo'
}, {
text : 'Marks',
width : 200,
dataIndex : 'obtainMarks'
}],
dockedItems : [{
xtype : 'pagingtoolbar',
id : 'pagingtoolbarId',
pageSize : 10,
dock : 'bottom',
displayInfo : true
}]
});
And in controller i am dynamically creating store and binding it to grid.For this i had written code as-
getAllPapers:function()
{
var paperlistStore=Ext.create('Balaee.store.qb.QbqnsStore',
{autoLoad: {params:{start:0, limit:10}}});
proxy= paperlistStore.getProxy();
Ext.apply(proxy.api,{
read:'index.php/QuestionBank/qbpaper/getUserAllQuestionPaper'
});
Ext.apply(proxy.reader,{
type:'json',
root:'questions'
});
Ext.apply(proxy.writer,{
type:'json',
root:'data'
});
var answers = '{"data":[';
answers = answers + '{"userId":1}';
answers =answers+']}';
console.log(answers);
paperlistStore.load({
params:{
data: answers
},
callback: function(records,operation,success){
console.log(records);
console.log("Successfully data send");
},
scope:this
});
var temp2=Ext.getCmp('QbqnsResultmainId');
temp2.removeAll();
var worldChaptor1 =Ext.create('Balaee.view.qb.qbqns.allQuestionPapers');
var resultView = Ext.getCmp('pagingtoolbarId');
console.log(resultView);
resultView.bindStore(paperlistStore);
temp2.add(worldChaptor1);
}
All this is working correctly.But grid is showing only 3 records per page instead of showing 25 records as per grid's paging function's dispaly message"displaying 1-25 of 280". So what changes i need to make in order to diaplay such 25 record per page.