ORA-01036: illegal variable name/number

Question

Hi all
Im trying to sort out this issue. I'm using Oracle database and C#, The error I got System.Data.OracleClient.OracleException: ORA-01036: illegal variable name/number. I don't know how I can solve it. I tried to remove the @ in the parameters or even replace them like p.Course_id, then ?p.course, p_course_id but nothing changed.
Please help sort out this issue. Thank you


My code





  command.Parameters.Add("course_Id", OracleType.Int).Value = course_Id;
  command.Parameters.Add("question", OracleType.VarChar).Value = question;
  command.Parameters.Add("posterName", OracleType.VarChar).Value = posterName;
  command.Parameters.Add("blogdate", OracleType.DateTime).Value = blog_date;