Implementing PayPal subscription with no trial period -

i using code subscription paypal payment

<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">         <input type="hidden" name="cmd" value="_xclick-subscriptions" />         <input type="hidden" name="business" value="a@a.com" />         <input type="hidden" name="item_name" value="this buy" />         <input type="submit" value="subscribe!" />         <input type="hidden" name="currency_code" value="gbp"/>         <input type='hidden' name='custom' value='777sdfsdf' />         <input type='hidden' name='invoice' value='103' />          <input type="hidden" name="a1" value="0" />         <input type="hidden" name="p1" value="1" />         <input type="hidden" name="t1" value="d" />         <input type="hidden" name="a3" value="10.00" />         <input type="hidden" name="p3" value="1" />         <input type="hidden" name="t3" value="d" />         <input type="hidden" name="src" value="1" />         <input type="hidden" name="srt" value="52" />         <input type="hidden" name="sra" value="1" />                 </form> 

this work fine 1 day of trial period requirement don't want give free trial user , when use

<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">         <input type="hidden" name="cmd" value="_xclick-subscriptions" />         <input type="hidden" name="business" value="a@a.com" />         <input type="hidden" name="item_name" value="this buy" />         <input type="submit" value="subscribe!" />         <input type="hidden" name="currency_code" value="gbp"/>         <input type='hidden' name='custom' value='777sdfsdf' />         <input type='hidden' name='invoice' value='103' />          <input type="hidden" name="a1" value="0" />         <input type="hidden" name="p1" value="0" />         <input type="hidden" name="t1" value="d" />         <input type="hidden" name="a3" value="10.00" />         <input type="hidden" name="p3" value="1" />         <input type="hidden" name="t3" value="d" />         <input type="hidden" name="src" value="1" />         <input type="hidden" name="srt" value="52" />         <input type="hidden" name="sra" value="1" />                </form> 

i following error when user click , go paypal

invalid first trial period. must specify valid values a1, p1 , t1 parameters subscription. 

my finding search , find there should @ least 1 trial period , didn't able find how implement no trial period using above method don't want change use other way of payment in paypal

fyi : using sandbox testing , hope same situation in live paypal environment

trial period not required. however, periods must valid (ie cannot have 0 length).

drop zero-length period , list periods want. calling period 1 becomes period 0 (which period, in example).