无线支付异步通知php isSign=false

java安卓端发送的数据

partner="20883115755*****"&
out_trade_no="20140911172717000000113"&
subject="充值(1)"&
body="“**”是阅读的通用货币，可用来购买付费书籍。"&
total_fee="0.01"&
notify_url="http%3A%2F%2Fapi.tutuyun.cn%2Fpay%2ForderNotify"&
service="mobile.securitypay.pay"&
_input_charset="UTF-8"&
show_url="http%3A%2F%2Fm.alipay.com"&
payment_type="1"&
seller_id="***@***.cn"&
it_b_pay="30m"
&sign="VUMZipXeqcfb4aEswK8cxWH%2FECiboNINd6aWDAnjY1efR1q4B1P4id%2FbT7Ee6SJJAzOLfH2KWM2PlM16TZ7S%2FmDqb%2FIqxGZyIZQWYsuxkClbPb4OXzDTXu%2BIuEEtErn19LSKSRhW0kkcXIBi61IVfB1YT5L%2FS9UcLVqEThdAJUo%3D"&
sign_type="RSA"

php服务端接收的异步通知
array {
["discount"]=>
string(4) "0.00"
["payment_type"]=>
string(1) "1"
["subject"]=>
string(15) "充值(1)"
["trade_no"]=>
string(16) "2014091154703582"
["buyer_email"]=>
string(15) "134****@qq.com"
["gmt_create"]=>
string "2014-09-11 17:05:13"
["notify_type"]=>
string(17) "trade_status_sync"
["quantity"]=>
string(1) "1"
["out_trade_no"]=>
string(23) "20140911170441000000110"
["seller_id"]=>
string(16) "20883115755*****"
["notify_time"]=>
string(19) "2014-09-11 17:05:14"
["body"]=>
string(75) "“**”是阅读的通用货币，可用来购买付费书籍。"
["trade_status"]=>
string(14) "TRADE_FINISHED"
["is_total_fee_adjust"]=>
string(1) "N"
["total_fee"]=>
string(4) "0.01"
["gmt_payment"]=>
string(19) "2014-09-11 17:05:14"
["seller_email"]=>
string(14) "***@***.cn"
["gmt_close"]=>
string "2014-09-11 17:05:13"
["price"]=>
string(4) "0.01"
["buyer_id"]=>
string(16) "20880129585*****"
["notify_id"]=>
string(34) "8d12f62fdc6b9610078554658bcaf69f6k"
["use_coupon"]=>
string(1) "N"
["sign_type"]=>
string(3) "RSA"
["sign"]=>
string(172) "HwA2hvfs/94Vq++JI81frXD3vI3e6Brc7W3ZoAuYPolIwBNxXAMSMPW2x+usKxvM042NUg6UaUVMTPYlwgIGJKVw8MjuJTdTPQ+UwokpZ+wonBaxZDUW0yASnoOaNXd38OoK5kfv9yflrdXIxwO+y5wggn3092Tp38NXPWhlV+w="
}

请问php服务端在signverify时 为什么出现了issign = false的错误