Yahoo API credentials :Response for Merchant password update displays as <error>

Realm : mercury

1.Create yahoo API credentials content-type as "application/xml"

{ "onBehalfOfAccountId" : "yTMCt-rZDE-h0Ldu-w24f", "onBehalfOfPassword" : "TSATrialYahoo55", "accountId" : 586827 }

2.Add header as "application/xml" in Accept

3.Send a request.

Actual result:

<error>
<message>Merchant Password updated</message>
</error>