Can not create trigger with trigger expression like {H6:log[/data/logs/test.log,(incorrect|FAIL)].last(0)}=0

When creating trigger with trigger expression like "

{H6:log[/data/logs/test.log,(incorrect|FAIL)].last(0)}

=0", then after clicking "Save" button got the following error:

"Incorrect curly braces count in expression.
Check expression part starting from "

{H6:log[/data/logs/test.log,(incorrect|FAIL)].last(0)}

=0"

In case I am using the following trigger expression "

{H6:log[/data/logs/test.log,"(incorrect|FAIL)"].last(0)}

>1" then all is working fine.