Type.GetType("namespace.a.b.ClassName") returns null

Type.GetType("namespace.qualified.TypeName") only works when the type is found in either mscorlib.dll or the currently executing assembly.

If neither of those things are true, you'll need an assembly-qualified name:

Type.GetType("namespace.qualified.TypeName, Assembly.Name")

You can also get the type without assembly qualified name but with the dll name also, for example:

Type myClassType = Type.GetType("TypeName,DllName");

I had the same situation and it worked for me. I needed an object of type "DataModel.QueueObject" and had a reference to "DataModel" so I got the type as follows:

Type type = Type.GetType("DataModel.QueueObject,DataModel");

The second string after the comma is the reference name (dll name).

Try this method.

public static Type GetType(string typeName)
{
    var type = Type.GetType(typeName);
    if (type != null) return type;
    foreach (var a in AppDomain.CurrentDomain.GetAssemblies())
    {
        type = a.GetType(typeName);
        if (type != null)
            return type;
    }
    return null;
}