checkbox to radio button

Hi all,

in the interface we used checkbox to select multiple, now due to some reasons user wants to select one item at a time so am thinking to go with radiobutton 

is that right way or do we have any other options? 

and even i have checked with radio button but am getting this error, hope nothing difference b/w check box and radio button

can anyone suggest me? Thanks in advance ,if anyone can advice on this

I have passed choice lables and choice values with equal length.Same error is hitting once I select radio button.