调用RfcCallReceive成功，返回参数没有回来

用c++开发rfc的接口，

1、我用的是连接串（TRACE=1 CLIENT=%s USER=%s PASSWD=%s ASHOST=%s SYSNR=0），连接成功。

2、输入参数是两个int数据，输出参数是一个int，我定义了：RFC_PARAMETER          exporting[2], importing[3];

       importing[0].name = "NUMC1";

     importing[0].nlen = 5;

     importing[0].type = TYPINT;

     importing[0].leng = sizeof(RFC_INT);

     importing[0].addr = &nNum1;

     importing[1].name = "NUMC2";

     importing[1].nlen = 5;

     importing[1].type = TYPINT;

     importing[1].leng = sizeof(RFC_INT);

     importing[1].addr = &nNum2; 

     //SAP_CHAR cOut[6];

     exporting[0].name = "NUMC3";

     exporting[0].nlen = 5;

     exporting[0].type = TYPINT;

     exporting[0].leng = sizeof(RFC_INT);

     exporting[0].addr = &nOut;

3、调用RfcCallReceive

         rfc_rc = RfcCallReceive (rfc_handle,                                   function,

                                   exporting,                                   importing,

                                   tables,                                   &exception);

      这个成功，但nOut没有返回回来，还是我的初始值。

      麻烦哪位大虾解答。