Hello all. New to this forum (so, hello

) and new to Crystal Reports and judging by what I have seen, this is the best place to ask for some advice.
I am currently developing my second ever Crystal report (shows how new I am) and have hit a bit of a snag with the parameter fields I wish to use.
I have taken over the job of report writing from someone who wrote all of our company's reports in Crystal 8.5. The company has decided to update to Crystall 11 so I'm stepping through coverting old reports and writing new ones.
The problem I have with the parameter field is related to Crystall 11's lack of appreciation for a Null value. The older reports we used always (8.5)contained a 'select for all' option in the parameter list to select all values (e.g. all suppliers). I am running into trouble trying to adopt this logic to Crystall 11.
I am using Crystal 11 as a standalone product and my database connection is via Advantage over a network, if that makes sense. Our databases are custom tables built in code.
I have a table called 'Supplier' which details supplier info. When you run my report you can select certain suppliers or all of them. As the table is so large, if you select the '>>' option in the parameter menu to select all the records it takes ages to move them all across. It would be nice to have a 'select all' option in parameter list (or a blank one to leave for all) but as I'm using a dynamic parameter this can't happen.
I was trying to add another parameter that asked the question 'Do you wish to searh all the suppliers'. I was hoping that if the answer was 'yes' then the search function could run without having to select a supplier from the list. If the answer was 'no' the prog could popup the supplier parameter. I don't think this will work in Crystal as I don't think you can select a parameter based on a previous parameter selection. Or am I wrong here?
Basically, what i'm after, is a Crystal 11 solution to the old 8.5 solution of the 'select all' value, without having the delay caused by the '>>' button.
Has anyone got any ideas about how this could be done? My parameter fields are currently 'date', 'supplier' and 'product variety'. Do I need to amend these or add something new? Can I actually program Crystal so that it displays a parameter based on a previous paramter input?
Many thanks in advance all, any help would be much appreciated. If you need to know anymore please ask.

Regards. Funky.