When use a radio button in the option To modify Link the value of the
selected button does not appear checked, the two used buttons appears
unselected. it can help me?

You have some pluguin that she returns SELECT eg: Format_Select_Field?

My code:
<!-- Delivery -->
<div class="row clear">
<label for="Contact_Name" class="name">Faz entrega em domicilio?:</label>
<div class="value">
<%Plugins::ULTRAGlobals::Format_Radio_Field('Entrega')%>

<%loop radio_loop%>
<input name="<%field_name%>" id="<%name%>" type="radio"
value="<%name%>" <%if selected%>checked<%endif%> />
<label for="<%name%>"><%value%></label>
<%endloop%>
</div>
</div>

__________________________________

HTML Results:
<!-- Delivery -->
<div class="row clear">
<label for="Contact_Name" class="name">Faz entrega em domicilio?:</label>
<div class="value">
<input name="Entrega" id="Nao" type="radio" value="Nao" />
<label for="Nao">Nao</label>
<input name="Entrega" id="Sim" type="radio" value="Sim" />
<label for="Sim">Sim</label>
</div>
</div>

____________________________________