未处理的NullReferennceException,求大神助攻

this.Initialization();

            //初始化Listview
            soLayers layers = mainform.axSuperMap1.Layers;
            soLayer layer = layers[mainform.cmbLayerName.Text];
            soDataset objDt = layer.Dataset;
            soDatasetVector objDtv = (soDatasetVector)objDt;
            soRecordset objRd = objDtv.Query("", true, null, "");

            soFieldInfo fieldInfo = null;
“System.NullReferenceException”类型的未经处理的异常在 WindowsFormsApplication13.exe 中发生 其他信息: 未将对象引用设置到对象的实例。
求大神助攻