Calling pgsql function from delphi

I have pgsql 7.2.2 running on linux 8. Client is win2k running Delphi6
ODBC version : 7.2.5

Create function get_machine_detail( smallint) return text as ...... language
'plpgsql'

Function was created and worked by testing from sql window in pgAdminII.
I am trying to call this function via delphi ADOdataset commandtype :
storedproc

with storedproc : It kept giving me an error stating that the parameter
setting is incorrect.

Calling using adodataset with commandtype : commandtext give me the correct
answer.
Any suggestion. Thanks
samira