AdWords API how do i start to use the Adwords api

hi,i want to use some Adwords api. and i have got developer_token and application_token, i use the demo of get_keyword_variations.php . But it returns "List of additional keywords to consider has 0 variation (s). List of popular queries with given seed has 0 variation(s).", it shows maybe th

AdWords API how do i start to use the Adwords api

i have got developer_token and application_token, i use the demo of get_keyword_variations.php . But it returns "List of additional keywords to consider has 0 variation (s). List of popular queries with given seed has 0 variation(s).", it shows maybe the method of getKeywordVariations not work ri