C sharp - Error de sintaxis (falta operador) en la expresión de consulta 'amc.Id_Alumno = A.Id_Alumno INNER JO

protected void Leer()

        {

            string cadenaConexion = WebConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

            using (OleDbConnection cnn = new OleDbConnection(cadenaConexion))

            {

		cnn.Open();

        string query = "SELECT A.Dni, A.Apellido, A.Nombre, amc.id_alumMatCurso FROM Alumno A INNER JOIN AlumMatCursos amc ON amc.Id_Alumno = A.Id_Alumno INNER JOIN CursosMaterias cm ON amc.id_alumMatCurso = cm.id_cursoMateria WHERE cm.id_Curso = @idCurso AND cm.id_Materia = @idMateria";

        OleDbCommand com1 = new OleDbCommand(query, cnn);

		com1.Parameters.AddWithValue("@idCurso", Convert.ToInt32(ViewState["idCurso"]));

		com1.Parameters.AddWithValue("@idMateria", Convert.ToInt32(ViewState["idMateria"]));

		OleDbDataAdapter da = new OleDbDataAdapter(com1);

		DataTable dt = new DataTable();

        da.Fill(dt);

		GridCargaAsistencia.DataSource = (dt);

		GridCargaAsistencia.DataBind();

            }

        }