Formating a radio

I have a form with a text field that is a radio. It´s related to a valuelist containing 4 options.

In SmartClient I can see the options as I want, from up to down, but web client show it as two groups. I mean:

SmartClient:
OPTION 1
OPTION 2
OPTION 3
OPTION 4

WebClient:
OPTION 1 OPTION 3
OPTION 2 OPTION 4

How can I solve this?