rsyslog configuration syntax

I need to take several actions for some log messages. For example I want to log them to different files according to severity.

Everything is ok if I use this:

if $programname == 'myprog'                                       then -/var/log/myprog.log
if $programname == 'myprog' and $syslogseverity-text >= 'warning' then -/var/log/myprog-alert.log
if $programname == 'myprog' ~

This log every messages emitted by 'myprog' to /var/log/myprog.log
This log only warning and error message emitted by 'myprog' to -/var/log/myprog-alert.log
And the processing is then stopped (thanks to '~')

.

I's like to have something sexier:

if $programname == 'myprog' then {
    *.*         -/var/log/myprog.log
    *.warning   -/var/log/myprog-alert.log
    ~
}

But this later construction, albeit accepted by rsyslog, do not filter against programname.
For example every messages are written to /var/log/myprog.log even when originating from whatever process.

.

Anyone can explain where is my mistake or misunderstanding ?

.

Final method, from answers below:

use a "modern" rsyslogd. Version > 7.x.y
use this syntax:

if $programname == 'myprog' then {
    *.warning   -/var/log/myprog-alert.log
    *.*         -/var/log/myprog.log
    *.*         stop
}

or this one:

if $programname == 'myprog' then {
    *.warning   -/var/log/myprog-alert.log
                -/var/log/myprog.log
                stop
}