Ext gridPanel数据无法显示问题，急~~~

JScript code

//数据绑定加载
    GridBind: function (assessNo, solutionNo) {
        Ext.AssessSolutionGradeStistics.app.storeAssessScore.baseParams = {
            assessNo: assessNo,
            solutionNo: solutionNo
        };
        Ext.AssessSolutionGradeStistics.app.storeAssessScore.load({
            params:
            {
                start: 0,
                limit: 20
            },
            callback: function (r, options, success) {
                if (success == false) {
                    Ext.MessageBox.alert('提示',"加载数据失败，无对应数据或者系统出现异常！");
                }
                else {
                }
            }
        });
    }

//grid控件显示
 this.storeAssessScore = Ext.AssessComm.AssessStore("/AssessStatistics/GetAssessSolutionGrade");
        this.gridCmAssessScore = new Ext.grid.ColumnModel([
                {
                    header: '机构名称',
                    width: 60,
                    sortable: true,
                    dataIndex: 'TargetName'
                },
               {
                   header: '方案名称',
                   width: 60,
                   sortable: true,
                   dataIndex: 'SolutionName'
               },
              {
                  header: '考核结果得分',
                  width: 60,
                  sortable: true,
                  dataIndex: 'ItemScore'
              }
        ]);
       
        this.gridAssessScore = new Ext.grid.GridPanel({
            id: 'AssessSolutionScoreList',
            name: 'AssessSolutionScoreList',
            region: "center",
            colModel: Ext.AssessSolutionGradeStistics.app.gridCmAssessScore,
            store: Ext.AssessSolutionGradeStistics.app.storeAssessScore,
            frame: true,
            border: true,
            enableHdMenu: false,
            sm: new Ext.grid.CheckboxSelectionModel({ singleSelect: true }),
            bbar: new Ext.PagingToolbar({
                store: Ext.AssessSolutionGradeStistics.app.storeAssessScore,
                pageSize: 20,
                displayInfo: true
            })
        });

jason后来获取到的数据为：

{'success':true,'data':[{"AssessNo":3.0,"OrgId":0.0,"TargetCode":"313","TargetName":"海沧区东孚卫生院","SolutionNo":122.0,"SolutionName":"福建省基本公共卫生服务项目考核标准","ItemPrice":56.0,"ItemScore":56.0},{"AssessNo":3.0,"OrgId":0.0,"TargetCode":"305","TargetName":"同安区西柯卫生院","SolutionNo":122.0,"SolutionName":"福建省基本公共卫生服务项目考核标准","ItemPrice":112.0,"ItemScore":83.0}],'totalcount':2 }

但是前台的gridPanel无法显示，storeAssessScore的load事件中的callback方法的success参数值返回了false
请问哪里出了问题？？？
请大家帮帮忙看一下，谢谢了！！！

按钮事件响应代码：
JScript code

//获取选中的数据
var assessNo = Ext.AssessSolutionGradeStistics.app.cmbAssessNo.getValue();
                var solutionNo = Ext.AssessSolutionGradeStistics.app.cmbAssessSolution.getValue();
//调用方法绑定数据
                Ext.AssessSolutionGradeStistics.app.GridBind(assessNo, solutionNo);