Webusercontrol loaded from another Webusercontrol not wiringup click event in first button click

Question

I have an .aspx page which has a LinkButton that loads a WebuserControl (UC1) to load a main image. When this Image is clicked another Webusercontrol (UC2) is loaded (UC1 is loading UC2).

UC2 is loading fine but when the button is clicked. Click event is not fired the first time. Click the same button again and event fires.

Why the UC2 (loaded through another webusercontrol) not catching the click event the first time button is clicked