Error with Trigger

[bdo]

Hi,
When setting this Trigger expression :
(({localhost:rs.last(0)}>1000)|({localhost:ws.last (0)}=0))&({localhost:sla.last(0)}=1)
What i want is : ( Condition1 OR Condition2 ) AND Condition3
I've got this error : Unable to get value for functionid [11232]

Is there a mistake with my expression ?
Used Version :
ZABBIX 1.1beta2
Thanks
Bertrand