I have form below which contains a text field and a button. when i start typing it shows hints from my database and on clicking button or hiting enter key it displys search results. ajax technology is used for both hints and search results and it is working well but

THE PROBLEM IS THAT IT WORKS ONLY THE FIRST TIME PAGE LOADS OR ONLY AFTER REFRESHING THE PAGE. IF I WANT ANOTHER SEARCH IT DOESNT RESPOND, JUST SHOWS THE PREVIOS SEARCH RESULT UNLESS THE PAGE IS REFRESHED.

 <input type="text" id="txt" onkeyup="showhint(this.value)"/> 
<input type="button" value="search" onclick="searchresult()"/>

what kind of problem is this?? any solution?? plz plz plz