unserialize not working
===

i am trying to unserialize string that is stored in mysql table. 

following is the string stored in mysql table.

    a:3:{s:15:\"purchase_amount\";d:500;s:4:\"more\";d:7;s:4:\"less\";d:11.5;}

at the time of insertion i had written following code.

    addslashes(serialize(array('purchase_amount' => $values['purchase_amount'], 'more' => $values['transportaion_cost_gretter'], 'less' => $values['transportaion_cost_lesser'])))

At retrieval i had written followin code.

    stripslashes(unserialize($row->getTransportaionCost()))

i am getting following error.

    Notice: unserialize() [function.unserialize]: Error at offset 5 of 98 bytes 

can any one tell me what is the problem ?