Hidden field does not have value

Dear Support,
I am now facing the problem with hidden field

array( 
                            'id' => 'hidden_value',
                            'type'=>  'hidden', 
                            'std' => 'Y',
                    ),

The above code is not getting value in rendered field can you please help me. This is second (Project) time I undergone the same problem I thought it would be the problem in my defination but now I can not resolve this can you please tell me what it could be. It would be really helpfull I am stuck here
Thanks & Regards
Calpaq