Datatypes in PL/PSQL functions with multiple arguments

Hello-

  This is my first foray into pl/psql so forgive me if I sound totally incompetent.

  I've been writing a few functions, and have come across some screwing data typing issues.

  When creating a function which accepts a single argument, things work just fine, variable can be used throughout the function as expected with no modification.
  When creating functions containing two or more arguments, I have to explicity cast the arguments whenever I use them (loading/casting into another variable is an option, haven't tried though) to prevent runtime errors.  The functions get called just fine, but then run into problems using any of the given arguments.

  Has anyone had any experience with this?  Please advise!

Thanks!
Benjamin

select version();
                                                version
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 PostgreSQL 7.4.7 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.4.1 (Mandrakelinux 10.1 3.4.1-4mdk)