I have done more directory submission in good PR directory submission sites. but still not approved why????
Because good directories have very high load of websites. That's why they take time to approve your link.
some can take a long time up to 1-2 months for the higher PR directories. Its often the lower PR/alexa directories that approve quickly. Also some of them may limit sites with PR1 and higher to be listed in their directory. So if you have a PR n/a or 0 you may not be accepted. Another thing check to make sure your following all of the directory guidelines when submitting.
I agree with @daones, some sites will approve based on the category in which you submitted.., you need to choose right category for your website.., rate approval is low if you place your website in wrong category..
Have you read the guidelines of the directories well? If you are submitting websites in wrong category there is possibility of getting rejected.
Find instant approval directories with high page rank . also always find relevant category for submission.