(Have now registered). Spent all day yesterday trying to fix this and am still stuck. Help much appreciated! I'm not able post the PL/SQL functions (or reduced versions) as they are a) complicated, b) legacy and c) not for public consumption. Sorry! I'll elaborate as best I can. There are a total of four cases:

1) PL/SQL function returns integer, binding works
2) PL/SQL function returns cursor, binding works
3) PL/SQL function returns integer, binding doesn't work
4) PL/SQL function returns cursor, binding doesn't work

For the cursors I am then SELECTing the relevant id value INTO the bound variable. As far as I can tell, the only difference between the working and non-working cases is that the ones that don't work are binding to a value which lives in a different schema to the called function (i.e. a foreign key pointing to a different database), whereas those that work are in the same schema. Is the DBI getting lost in the redirection?
Have run the code on another machine, with various versions of Perl/DBI, including the latest. DB is Oracle 10. The functions are all definitely executing correctly. It very much looks to me like the problem lies with (or is manifested by) the binding.
Thanks for your help!