Autocomplete Textbox Using Database Return Value in ASP.NET

Hi,

I use autocompleteExtender to key into a textbox, the value will come from a database table.setting UseContextKey=true,and the ContextKey depend on dropdown control.

When I click the dropdown first,the value come from a database table is what I need.In the meanwhile,I found the dropdown value is wrong,I select another dropdown value,and enter same keyword into the  textboxand,but the value come from a database still show the privious value,not the correct value what I click the dropdown again.

For example,firstly,if the dropdown value is A,I enter keyword test into the textbox,the value what come from a database table is A1,but in the same time,I found the dropdown value should be B,I change the dropdown value is B,and I enter keyword test into the textbox again,the value what come from a database table still is A1,not show the correct value B1.

So,how to fix the code?Thanks.