As a simpler solution....

You have created a Calendar table in Oracle (this is the recommended solution for your problem, incidentally).  Now, make your query look like:

SELECT Calendar.Time, MyAppt.Time, MyAppt.Details
FROM Calendar
LEFT JOIN MyAppt
ON Calendar.Time = MyAppt.Time

The left join will show all the results from the Calendar table, plus any matching appointments.  (There is a tricky bit in getting the join condition between the tables set up right, that depends on how you set up the Calendar table.)

You can also do this in Crystal, using the link tab when setting up your datasource.  But, when at all possible, I recommend doing it in the source database.  It is more powerful, more flexible, and more efficient.

I presume you have a DBA for this database?  Talk to him/her, and get some assistance.  After all, it's in their best interests for you to get this done right, too.

The appointment date is in one table, and the time is in another?  That's, well, goofy.  Given that Oracle doesn't store date or time values, but datetime values, what is the date on those time values?

OK, if you haven't created the Calendar table yet, then this is a good time to do so.  Actually, just make it a Numbers table, as that's more flexible.  For your purposes, make it a two-column table.  The first column contains the integers 0 through, say, 400.  The second column is equal to the first column times 15.

In order to do your join, it should look like:

PROCEDURE ApptProc (startdate IN DATETIME, enddate IN DATETIME) 

IS
BEGIN

SELECT 
DATEADD("mi", Numbers.ID15, TRUNC(startdate)) AS ApptDate,
ApptDetails.*
FROM Numbers
LEFT JOIN ({{insert your existing SQL here}}) ApptDetails
ON Numbers.ID15 = DATEDIFF("mi",TRUNC(ApptDetails.ApptTime),ApptDetails.ApptTime)

END

Well, you'll actually need to add a WHERE clause to only show the times you want.  But, that should give you the starting point.

The reason to use the left join is twofold.  One, it is significantly more efficient, from a processing point of view.  You are only processing the query once, and you are processing everything on the server.  Two, it is significantly easier from a management point of view down the road.  Even if the SQL above looks complicated to you, it's a lot easier to come back and modify a year from now than a jury-rigged collection of subreports will be.  Take it from someone who's been there.

One quick note about "boot camp" training.  Nine times out of ten, those classes won't actually teach you much.  They are really designed to take already experienced (especially self-taught) programmers and/or admins, fill in any gaps in their knowledge, and prep them for a certification exam.  They are so quick, because they really zip through a lot of the material, without going in depth.