DqLinq to MySql Inheritance issue

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Create a simple table People with 5 attributs
id, firstName, lastName, type, grade
2. Create a simple scheme as
[Table]
[InheritanceMapping(Code = 0, Type = typeof(Normal))]
[InheritanceMapping(Code = 1, Type = typeof(Student))]
public partial class People
{
 //All atributs
 [Column (IsDiscriminator = true)]
 public int type;
}

3. Make a request
var entities = from p in provider.People.OfType<Student> select p;
foreach (Student s in entities)
//...

What is the expected output? What do you see instead?
Normaly it lists all the students in the table but it throws an exception
"S0133: Implement QueryMethod Queryable.OfType."

What version of the product are you using? On what operating system?
Using DbLinq 0.20.0 on Windows 8

Please provide any additional information below.
Trying with "var entities from p in provider.People where p is Student select 
p;" but it throws another exception about parameter.

Original issue reported on code.google.com by joris.mi...@gmail.com on 9 Jun 2012 at 7:32