Web Forms :: When Does Checkboxlist Will Populate Data Using Parameters?

i have a checkboxlist with a controlparameter. the flow of my page is

1) enter value into textbox eg: empid - 098765

2) on text box leave event ,im gettin data from db based on value enter in textbox and fill the labels in form

eg: select * from empmaster where empcode = '098765'

lblcode = MD lbldesignation = "Managing director'

3) based on the value filled in label am populating checkboxlisteps in text

select skill from behaviour where jobcode = lblcode.text (MD)

i have write all the above 3 steps in textbox_textchange event.Now i wanted to know after which event, checkboxlist will populate.coz iniside the textbox_text change event when i count the checkboxitems it always says 0.but it got items.so when it will populate checknboxlist?