That is just one issue with link building. It is also a bad way to go about building links.
Trying to index a backlink is mostly out of your control, but if you know what you're doing you can help the process along a bit.
Don't try to index a backlink. Acquire links from sites that are already indexed by Google and Bing. That is also the rub. You want results now and it will take time to curate those links. Especially if you have never done it before.
Google knows which sites are just link farms, and devalues them for ranking purposes. You have to find sites that are hard to acquire a link from. As a rule of thumb, the harder it is to acquire, the better it is.
Sites like these require you to curate a relationship with them. Write content they will post and as you get accepted then you can start linking out.
Remember this too, 1 link from a site like this is worth a 1000 links from sites anyone can post on !!!!