I added the max expression and fix it.

AND (select max(datediff(ss,last_batch,getdate()) ) FROM sysprocesses where blocked = @blocker) > 5

I got this error message when trying to run this script:

(1 row(s) affected)

(0 row(s) affected)

Msg 512, Level 16, State 1, Line 18

Subquery returned more than 1 value. This is not...