Boostrap modal pop up window issue

Question

Hi,

 

I am making a web page in asp.net c sharp. In Html design part i have applied bootstarp modal . Now aafter the click on button the anoher page is displaying but if i am selecting in that any dropdown textbox the page is going back to home page. i have applied the content ad upatepanel.could any one please help me to reslove the issue as soon as possible.