with googeling i've found this
Type type = Type.GetType(fully
qualified class name string);
from msdn:
typeName:
The assembly-qualified name of the type to get. See
AssemblyQualifiedName. If the type is
in the currently executing assembly or
in Mscorlib.dll, it is sufficient to
supply the type name qualified by its
namespace.
Return Value The type with the
specified name, if found; otherwise,
nullNothingnullptra null reference
(Nothing in Visual Basic).
so, ... i believe it was not found when you get null as the result
for more info for AssemblyQualifiedName
to get an idea of your fully qualified name just do
typeof(MyClass).FullName
typeof(MyClass).AssemblyQualifiedName