Unable merge cell

Unable merge cell

I fisrt time ZOHO office speadsheet.

i have problem on merge cell at my pc.

i unable to use merge cell icon.

The merge cell icon is not active...

is my pc need to update?

PC Specification

Windwos 10 pro

Intel Core 2 Dou CPU E7500 @2.93Ghz

Installed Memory = 2 GB

System type = 32 - bit Operating system