contact the vendors of the service and have patience.. google doesn't crawl every second

How new are the sites and where do you have backlinks? Craigslist is one of the best sites to have backlinks at, it is constantly getting crawled by the Big G.

A few questions (assuming your on-site SEO is all in good order):

(1) Are you prepared to divulge your keywords, or else present some information as to your SEO competition (on Google page #1, specifically)?

(2) When did you start your backlinking campaign?

(3) Precisely what sort of backlinking services have you purchased (i.e. what sort of backlinks are they? Profile backlinks? Blog comments? Mass article submissions? ...)

Without knowing what sort of competition you're facing and having something on which to develop an idea of your backlinking strategy, it'll be hard for anyone to tell you why you aren't seeing success, or whether there's anything wrong with your approach.

Not that anyone will likely be able to give you any concrete answers even with this information - but that, unfortunately, is just the nature of SEO. But I'm afraid right now, one cannot even make anything approaching an "educated guesstimate".

Besides that, and as far as "backlink checkers" are concerned, you will always see more backlinks displayed at Yahoo than you will Google, who tend to reveal very little (publicly, at least) - and quite often nothing at all - about your backlinks profile in comparison to Yahoo.

Are you using YSE to check backlinks? Google won't show many backlinks in their tool.

normally I use market samurai to check ranking and backlinks which uses yahoo site explorer to get the details for the backlinks. you can also try Link Diagnosis - examine your link competition which is free