PI7.4 SLD_UC failed to connect，RZ70 failed problem

hi，all

In PO 7.4
system(PI 7.4), I have configured the ECC and PO
system as  following link:

http://scn.sap.com/community/pi-and-soa-middleware/blog/2013/08/28/overview-configuration-guide-for-abap-backend-systems-integrating-with-aex.

But when I want to register in system landscape directory by
TCODE: RZ70, I failed, the message showed as following(the gateway host is the
PO system host IP):

Error: Used RFC destination: SLD_UC

           RFC call failed: Error when opening an RFC  connection (CPIC-CALL: 'ThSAPOCMINIT' : cmRc=19 thRc=7

And
the RFC destination SLD_UC connection  also failed too，the
configuration（gateway host = PO system ip） and  return message are

Here are other configurations in ECC system(EHP6 FOR SAP ERP 6.0) and PO system (PI
7.4).

1. In ECC client:

       1.1 RFC destination： SAP_PROXY_ESR and Connection Test success

1.2 RFC destination: PI_AEE  (target host is PO system host ip) and connection test success.

1.3 Integration engine configuration configured as following picture

And the check messages.

1.4 SLDAPICUST configuration

And it's test result.

1.5 SLDCHECK result

  1.6 profile parameters gw/acl_mode in tcode:RZ11,the value is changed to 0 already

1.7 in tcode SMGW, the sec info & seg info show like following two pictures and I have reload many times

1.8 The tcode sproxy result

2  In PO system:

2.1 URL:http://<PO host ip>:50000/sld,Path:Administration->server-settings,Section
datasupplier. The gateway host is the PO system ip address and Unicode gateway registration
id is SLD_UC  and restart SLD

2.2 the server-details-Data suppliers, all server threads are up

I really don't know why this RFC connection SLD_UC fail. Can anyone tell me the solutions? Thanks.