Cannot click Option Buttons when Protected

Hi guys,

I have this concern with regard to the Option Button (Form Control) i created found under Developer tab. The buttons work fine when the sheet is not protected. But when I try to protect the sheet, it won't work as it prompts an error that the sheet is protected. I mean, the sheet should be protected so that the formulas won't be erased.

I tried the following:
- Unchecking "Lock and Lock Text" buttons under Protection of Format control
- Cells where i placed the Option Button are also removed from protection when I did format cells

Did I miss something? I know i miss something but I just can't figure it out.

Hope you guys could help me on this. Thanks!