Problems in SSIS land

Using SQL Server 2012, SSDT with Visual Studio 2012

There's an interesting article on MSDN: OLE DB Source discussing, among other things, how to use parameters when calling a stored procedure in an OLE DB Source component. The section "Specifying Parameters by Using Ordinal Positions" (about halfway down the page), shows an example using the AdventureWorks database. Unfortunately, the example doesn't work, at least not if you try to Preview the results.

Note that I want to use Preview as a sanity check that I've set things up correctly. Instead, it's driving me insane!

I set up my test using exactly the setup described:

1. OLE DB Connection Manager to AdventureWorks (I used the 2012 version for the test) 
2. OLE DB Source Component using the Connection Manager in step 1 
3. Data Access mode: SQL Command 
4. SQL Command text: EXEC uspGetWhereUsedProductID ?, ? -- copied from the web page 
5. Two variables created: User::StartProductId (int) and User::CheckDate (datetime), set to 0 and getdate(), respectively 
6. Two parameters in the SQL query Parameters window: Parameter0 mapped to StartProductId Parameter1 mapped to CheckDate 
7. back in the OLE DB Source Editor, clicked Preview ------->>> BOOM!  

"No value given for one or more required parameters."

 So, it seems that the documentation is wrong (or incomplete) on this point. Curious to see what was going on, I fired up Profiler to trace the calls. I was surprised to see this sequence:

declare @p1 int
set @p1=0
exec sp_prepare @p1 output,N'@P1 int,@P2 datetime',N'EXEC uspGetWhereUsedProductID @P1, @P2',1
select @p1
exec sp_execute 1,0,'01-01-1992 01:01:01:000' 

So, I learned that the Preview did not use the variable values I had set. Why?

Since the ordinal positions method didn't work, I tried the second option: Specifying Parameters by Using Names

To do this, I changed my SQL command to:

EXEC uspGetWhereUsedProductID 
    @StartProductID=?,
    @CheckDate=?
;

And changed the mappings to:

@StartProductID --> User::StartProductID
 @CheckDate --> User::CheckDate

Then I clicked Preview again. -- Same result ----> BOOM! Same error message. Still didn't use my variable settings So, this is totally messed up.

HOWEVER! When I actually execute the task under debug in SSDT, it runs fine, uses the variable values I set, etc.

So, the big questions:

1. Why does Preview bomb? From what I can see in the trace, it shouldn't. That is, it properly prepares the call to the stored procedure (except for my variable values), FWIW I copied the statements from Profiler and ran them fine in SSMS. So why does this fail in SSDT debug? 
2. Why doesn't it use my variable values? 
3. Where did the date '01-01-1992 01:01:01:000' come from? Is it just a historical reference to SQL-92?