Right Click Doesn't Show Option to Protect Cells on All Pages

My excel project has five sheets. When I right click on any cell within two of the worksheets, it shows the option to protect cells with XLS Padlock. But the remaining sheets when I right click, the XLS options are not visible, so I can’t hide those formulas in those worksheets. Has anyone every experienced this?

No, and it is strange. Which Excel version are you using? Is it up-to-date? Do you use VBA or .officeUI to customize the menus/toolbars?