sybase_query return

Hi, I have a problem. I am using sybase_query to update a statistics table, and then reset an external cache server. These operations come one after another in the script. The ideea is that the new thing will be cached again the next time it's called, but the cache beeing reset will force it to be the newest thing. The problem that I am facing is when I put it into a big traffic site. Then it looks like the cached image is an older one. No ideea why. I am assuming that sybase_query returns before finishing the query execution!? And then the cache gets reset but beeing constantly called it takes still the old thing from the database? Any ideeas? I would appreciate! Calin