To get the dropdownlist values from usercontrol(ascx) in the web page(aspx)

hi all, Greeting to all,

i'm using a user control which has dropdown list and text box. i use this across four pages(aspx). i have a button control in the four pages . i need to get the values of the dropdown list control  and text box in the button control(this is not in user control) event.

i tried like this:

i defined a function in the usercontrol and got the values and called this function from other four pages(aspx). then it shows exception "Object reference not set to an instance of an object".

Kindly post the code and give your valuable ideas. Thank You.