Indexed sitemap links varying dramatically

Indexed sitemap links in Google Webmaster tools are varying dramatically

[VirginTech]

Hi there.
Yesterday i submitted my sitemap to Webmasters tool and it showed me 700+sitemap links indexed in total. After few days (around 3-4 days) my webmaster account is showing me only 160 indexed links.So after seeing this I submitted my sitemap again and then again it showed me 700+ indexed links.
So anyone please tell me whats happening with these sitemap indexed links, I mean how my indexed sitemap links gets reduced autmatically after sometime.

Thanks in advance for any help!

Shahab khan

[edited by: tedster at 8:08 pm (utc) on Nov. 25, 2009]
[edit reason] no personal urls - see TOS [webmasterworld.com] [/edit]

[anallawalla]

Are you seeing any other clues? Is there a green tick, a red cross or a yellow exclamation mark icon? If some of the URLs present an error (could happen if the server is down), your URL count could go down. How many URLs are in the sitemap?

[VirginTech]

Sorry annallawalla i just saw your reply that's why replying too late.I hope you wouldn't mind it.
Anyway i am seeing a green tick there. In total my sitemap have 754 URLS with 433 indexed URLs. After some days total no of URL and indexed URL both comes down.

If you have any idea then do let me know about it.

Thanks
Shahab khan

[goodroi]

If your sitemap is using irregular characters it might be preventing Google from reading the entire sitemap. Make sure your sitemap validates properly.

Also remember that Google tries to only index pages with significant unique content. If some of your pages are very similar to each other Google might decide not to include all urls in their index.

To increase the probability that Google will index your pages you should #1) increase the amount of link popularity to your pages, #2) provide significant unique text on each page and #3) increase the amount of google toolbar users that visit your site & spend significant time on your site.

[VirginTech]

Ok goodroi thanks for the nice suggestion.