今天想整一个项目进解决方案出现的问题,“CommonTools.Common”的类型初始值设定项引发异常

“CommonTools.Common”的类型初始值设定项引发异常我在业务层写  int Id;
            CommonTools.ProcDB data = new CommonTools.ProcDB();
            CommonTools.Common.sCon = "server=.;User ID=sa;Password=wanglin;database=OnlineSuscribeSystem;Connection Reset=FALSE";
            SqlParameter[] prams ={
                                      data.MakeInParam("@WorkId",SqlDbType.VarChar,10,WorkId),
                                      data.MakeInParam("@Department",SqlDbType.VarChar,100,Department),
                                      data.MakeInParam("@WorkMainContent",SqlDbType.VarChar,100,WorkMaincontent),
                                      data.MakeInParam("@SubscribeTitle",SqlDbType.VarChar,100,SubscribeTitle),
                                      data.MakeInParam("@Pri",SqlDbType.VarChar,50,Pri),
                                      data.MakeInParam("@AddDate",SqlDbType.DateTime,8,AddDate),
                                      data.MakeInParam("@SubscriptionOrderContent",SqlDbType.Text,1000,SubscriptionOrderContent),
                                      data.MakeInParam("@FlowType",SqlDbType.VarChar,10,FlowType)
                };
            Id = data.RunProc("subscriptionEditionFillin", prams);
            return Id;
 CommonTools.Common.sCon = "server=.;User ID=sa;Password=wanglin;database=OnlineSuscribeSystem;Connection Reset=FALSE";
这句本来没有问题的,但是现在却出现问题，请达人指教.