an error while using pt-index-usage

[Ran Margaliot]

Hello,

I'm trying to run  pt-index-usage on MySql 5.5 (percona toolkit version 2.1.1) in the following way:

pt-index-usage  --password 'my_pass' --progress time,5 h=127.1,D=my_db mysql-slow.log

and I'm getting the following line:

h=127.1,D=my_db does not exist or is not readable at /usr/bin/pt-index-usage line 4385.

and afterwards it starts reading the slow-queries log file:

mysql-slow.log:   0% 46:39 remain

mysql-slow.log:   0% 01:03:43 remain

....

any ideas regarding the error I'm getting?