问微信支付失败？

生成的签名是 "{\"package\":\"Sign=WXPay\",\"appid\":\"wx16e90c52e36baea3\",\"sign\":\"565C37E90B699691C104DA5D988E2E3D\",\"prepayid\":\"wx171332289952445711c223000336146187\",\"partnerid\":\"1509155121\",\"webchatXmlPost\":\"<xml><return_code><![CDATA[SUCCESS]]></return_code><return_msg><![CDATA[OK]]></return_msg><appid><![CDATA[wx16e90c52e36baea3]]></appid><mch_id><![CDATA[1509155121]]></mch_id><nonce_str><![CDATA[alc2y9ovqcefIBSL]]></nonce_str><sign><![CDATA[A1F7B09B18053F392A2D2FA423ADA665]]></sign><result_code><![CDATA[SUCCESS]]></result_code><prepay_id><![CDATA[wx171332289952445711c223000336146187]]></prepay_id><trade_type><![CDATA[APP]]></trade_type></xml>\",\"retmsg\":\"OK\",\"noncestr\":\"alc2y9ovqcefIBSL\",\"retcode\":\"SUCCESS\",\"timestamp\":\"1531805549\"}"

支付却显示失败，请问是什么原因