Hi Zoran, again, and to answer my own question, this is what I did...
Suspecting that my SchedulerClient class wasn't being constructed at all, I copied some of the code out of the source for DNN Scheduler, and pasted it into the code behind a button on a dummy test module:
Stop
'''''''''''''''''''''''''''''''''''''''''''''''''''
Dim t As Type = System.Web.Compilation.BuildManager.GetType("Idonix.DNN.Modules.EC.MyriadMembership.MyriadMembershipImporter", True, True)
Dim param(0) As DotNetNuke.Services.Scheduling.ScheduleHistoryItem
param(0) = New DotNetNuke.Services.Scheduling.ScheduleHistoryItem
'''''''''''''''''''''''''''''''''''''''''''''''''''
'Get the constructor for the Class
'''''''''''''''''''''''''''''''''''''''''''''''''''
Dim types(0) As Type
types(0) = GetType(DotNetNuke.Services.Scheduling.ScheduleHistoryItem)
Dim objConstructor As System.Reflection.ConstructorInfo
objConstructor = t.GetConstructor(types)
'''''''''''''''''''''''''''''''''''''''''''''''''''
'Return an instance of the class as an object
'''''''''''''''''''''''''''''''''''''''''''''''''''
Dim C as DotNetNuke.Services.Scheduling.SchedulerClient = CType(objConstructor.Invoke(param), DotNetNuke.Services.Scheduling.SchedulerClient)
Note the 'stop' at the top that makes debugging/step through of the code possible, so long as the site is on your dev. machine.
Having done this and stepped through the code, I discovered firstly that I had the wrongly formatted AssemblyName/TypeName thing, but being able to experiment in the Immediate window of Visual Studio made it easy to fiddle until it came right.
I then discovered that my SchedulerClient class's constructor 'Public Sub New(item as ScheduleHistoryItem)' was missing (oops!), and so the objConstructor above was returning nothing. Having fixed that up all came good, and my scheduled job took off as expected.
If you put a 'Stop' line in the top of your DoWork() sub, you'll also hit the debugger when the code is at last called.
I hope this is some help.
Cheers,
Paul.