when I post ads there is a "Page was not found"

off the hip here, are you on a custom template? 

if so switch to uni and see if you can post. 

also, have you looked in your database to see if the insertion is happening? 

alternatively, uninstall ads and reinstall them. 

I have not modified the custom template.

and I uninstalled the  ads and installed it again ,but it still doesn't work

how can i  switch to uni ?

I deleted some things in the database, ii it the reason?

 you deleted some things in the database. thats promising.

which things did you delete from the database? 

Not delete,just emptied some things ,such as bx_ads_main  in the database.

would U like to have  a try at www.i4job.com?

I still have not resolve the problem, please help me !

i think you have more serious problems with your site than just the ads. yes ads are not working. however, i joined your site using the facebook connect, and it loaded some userID = 9 fellow named jerry. 

that is a severe problem. 

also seems your site is ate up with the chinese posters on the blogs. 

 How can I resolve it?