Social media links with ShareThis

Hi,
I've added some social media links generated by ShareThis.com and I'm having a couple of strange problems.

First, I guess the basic question is the ShareThis linking good to use at all?

Second, tag replacement doesn't seem to work properly. I started by adding
<span class='st_facebook' st_url="[[~[[*id]]]]"></span>
but for some reason when the page is rendered the st_url value just comes out as index.php?id=7 (for example) - i.e. it's missing the root url. Note, I've put this span in a chunk which I called on the template.

Third, if anyone reading this has any experience with the ShareThis linking could you tell me how to get the facebook link to include the content I specify - even putting it in og meta-data tags won't do it.

Thanks in advance.

1) yes we use the sharethis on our website, its fine, no configuration at all on the modx side as its all front end code.

2) [[~[[*id]]]] should produce the site_url, if not check site_url in config file. or try to output [[++site_url]] if nothing is shown then you know that the config variable site_url is not set correctly.

I've used [[++site_url]][[~[[*id]]]] as that's the only way I can get the full url to come out.
But at least it show's that [[++site_url]] is correct.

I tried sharethis and failed, I believe I used Bookmarkthis instead.

Here are some links regarding facebook. It can be tricky.

http://forums.modx.com/thread/96893/bookmarkthis-plugin?page=2#dis-post-524306

http://forums.modx.com/thread/92482/facebook-share---not-properly-working-please-help?page=2#dis-post-512542

My issues with facebook have been because I am using a forum and promoting forum posts.

http://forums.modx.com/thread/96491/facebook-shares-inside-discuss#dis-post-525105

Just to update on the Facebook problem with og tags - when I first tested a share I didn't have the og tags in the page. Apparently facebook caches a scrape of the page and that's it uses from then on, so even after I made the og changes they didn't appear to affect anything.
You can use https://developers.facebook.com/tools/debug/ to force facebook to rescrape the page after you make changes to see if they work.