Store procedure freeze when enter different value

[fredong]

I am using SQL Anywhere 9.0. I have a store procedure that has 5 parameters. Each time when I enter a value of a parameter it took 16 seconds however, when I tried to enter a different value on the same parameter it took 20 mins up. Is there way to trace the input and output or which table is the proc hitting? Any ideas? Thanks.

For example

Store procedure
----------------
Agingproc '08/20/06', 'TTT',NULL,NULL,NULL --works fine took only 16 secs

Agingproc '08/20/06', 'SSS',NULL,NULL,NULL --it took 20 mins to bring it up