Facing Error in Radiobutton - Webdynpro ABAP


I am using Radiobutton UI Element.

I have requirement of taking 5 Radiobutton in which user can only select 1 value.

So I have created 5 Radiobutton . I have binded KeytoSelect property to different value



RD1 its LA

RD2 its LB

RD3 its LC

RD4 its LD

RD5 its LE

So i have bound all these radiobutton to one attribute of node whose cardanality is 1 : 1 and type char2.

So when i execute it , on any event on screen it is giving me error

'The value entered is not in the list of allowed values.'

So i could not found the reason why it is coming. I have also tried to make one data element and domain and try to put

the values like LA to LC in its fixed value but again it is giving the same error.

Please suggest