Dear Friends,
I am developing open API integration with asp.net B2S, I got the below error message after I do the posting my values to enets uat by using sendPayLoad(txnReq, hmac, keyId) method.
Your valuable advice/solution appreciated.
Aside to this I have few more questions

I have my developer’s API Key ID and Secret Key, for merchant ID do I need to use my Client’s Merchant UMID received from eNETS?
Does it require test/host merchant application to any particular public IP that is allowed by eNETS (Like older method with UMID Posting to enets)?
Does it require any IP/Firewall config in my server where my merchant application hosted?
does it required to send email to enets to quote this error to know what is the issue?

 
Values:
I have used one of the shared credentials in the forum.
Secret KEY : 38a4b473-0295-439d-92e1-ad26a8c60279
API KeyID : 154eb31c-0f72-45bb-9249-84a1036fd1ca
MerchanID : UMID_877772003
txReq:
{"ss":"1","msg":{"netsMid":"UMID_877772003","tid":"","submissionMode":"B","txnAmount":"30.00","merchantTxnRef":"1392","merchantTxnDtm":"20180807 13:57:57:492","paymentType":"SALE","currencyCode":"SGD","paymentMode":"","merchantTimeZone":"+8:00","b2sTxnEndURL":"https://uat2.enets.sg/MerchantApp/sim/b2sTxnEndURL.jsp","b2sTxnEndURLParam":"","s2sTxnEndURL":"https://uat2.enets.sg/MerchantApp/merchantNotificationServlet","s2sTxnEndURLParam":"","clientType":"W","supMsg":"","netsMidIndicator":"U","ipAddress":"127.0.0.1","language":"en"}}
HMAC:
NmZiNzE5NDIyYTJlZDRhMDQ5MDYwYjE2N2YzMDU4NzVlM2E0N2M0M2U3NTVjNWJiOWQ4NzYzYzA2YzMxNTE1Mg==
I have verified the above hmac with the following link and its correct. ( did SHA256 and performed Base 64 encode)
https://www.xorbin.com/tools/sha256-hash-calculator
 
Response:
Please quote ERROR CODE=0010-50001 and ACTION CODE=3 with the below merchant information:
Merchant ID=UMID_877772003
Transaction Date Time =20180807 13:57:57:492
Merchant Reference=1392