Approval depends on a lot of factors, some of them are below:
– Selection of title (are you using too many commas in title? Are you using repeated keywords?)
– Description (is it a description written in third person narrative or it’s a string of keywords or it’s a sales pitch)
– Category (typically loans / insurance categories see a lower level of approvals)
– Email used (if you use gmail or yahoo accounts for submission you can expect slightly lower approval rates)
– Adsense / affiliate links on site (if you have a lot of pop up ads or adsense units, quality directories won’t accept your submission)
– Your website’s PR (unfortunately some directory owners think PR2+ websites are quality websites and they only approve those)

Hopefully if you keep the above mentioned factors in mind, your approval rate can increase.