strange sybase results

Hi,


I have a very strange issue with a php site which calls a function
within the sybase database (SQL Anywhere 8)


The call itself is like this:

include "../connect.syb.php";
syb_connect();
$s = "SELECT RoutingGetVon ( 'KP111', 2, 'X', '55555' )";
$q = sybase_query($s);
$x = sybase_fetch_row($q);
$r = $x[0];


Depending on the values in the function I get an value back or and
that's my problem not.

Sounds as the function has an error, but doing the same SELECT in ISQL
it returns the propper value always.


Adding a 
if ($r == NULL) echo "NULL";
shows NULL for all the non results


So my questions are:
- what can be the difference in a result from the same function, which
one time is the same as in ISQL and with other values it is different to
ISQL result?
- is there a way to get the raw result data shown? Maybe
sybase_fetch_row() works buggy (I tried with sybase_fetch_array() - it's
the same result)?
- any other ideas or suggetions?


Thanks for any help
Florian