well the one that worked is that :
Code:
{section name=field loop=$extra_fields}
{if $extra_fields[field].field_value eq "Y" && $extra_fields[field].field eq "Ship by mail"}
<img src="{$ImagesDir}/custom/ship_by_mail.gif" />
{/if}{/section}
so it looks like on the "$extra_fields[field].field" it wants the field name and not service name
thank you very much