How do i filter posts by one custom field and order by another custom field?

After looking at this:

https://www.ads-software.com/support/topic/203210?replies=9

and this:

https://codex.www.ads-software.com/Displaying_Posts_Using_a_Custom_Select_Query

I managed to retrieve posts by a custom field called “Backlab Artists”.
Now, I want it to sort by a second custom field called “rs_event”, which isn’t working.
Code looks like this:
`
$querystr = “
SELECT wposts.*
FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta
WHERE wposts.ID = wpostmeta.post_id
AND wpostmeta.meta_key = ‘Backlab Artists’
AND wpostmeta.meta_value = ‘”.$name.”‘
AND wposts.post_type = ‘post’
AND wposts.post_status = ‘publish’
ORDER BY wpostmeta.meta_value DESC
“;

Thanks for your help!