Continuous Selecting of Option Button

I made option button control.
In every click one of the option button, click event must be generated.
But if click one option button continuously, 2'nd click event does not be generated.
I cannot understand why this occurs.
Is there some property that can control this phenomenon in option button control?
Could anyone who know it let me know?
Thank you.

I'm a senior programmer.
Working at CamSight, Dental imaging solutions industry.