OleDb更新excel数据至少一个参数没有被指定值

想用C#更新这个表格，可是总出现异常，至少一个参数没有被指定值
代码如下
string fileName = @"C:\Users\Administrator\Desktop\ee.xlsx";
string excelConnectionString = "Provider=Microsoft.Ace.OleDb.12.0;Data Source=" + fileName + ";Extended Properties=\"Excel 8.0;HDR=Yes;\"";
OleDbConnection conn = new OleDbConnection(excelConnectionString);
conn.Open();
OleDbCommand cmd = new OleDbCommand();
cmd.Connection = conn;
string sql ="UPDATE [Sheet1$] SET A2='北京' WHERE A1='北京';";
cmd.CommandText = sql;
cmd.ExecuteNonQuery();