can you please check point (6) issue how to solve?
Last recorded SAML login failure:  2015-06-04T04:58:34.395Z
Unexpected Exceptions
  Ok
1. Validating the Status
  Ok
2. Looking for an Authentication Statement
  Ok
3. Looking for a Conditions statement
  Ok
4. Checking that the timestamps in the assertion are valid
  Ok
5. Checking that the Attribute namespace matches, if provided
  Not Provided
6. Miscellaneous format confirmations
  InResponseTo must be empty for Idp-init Browser POST Profile
7. Confirming Issuer matches
  Ok
8. Confirming a Subject Confirmation was provided and contains valid timestamps
  Ok
9. Checking that the Audience matches
  Ok
10. Checking the Recipient
  Ok
  Organization Id that we expected: 00D28000000WHXX
  Organization Id that we found based on your assertion: 00D28000000WHXX
11. Validating the Signature
  Is the response signed? true
  Is the assertion signed? true
  Is the correct certificate supplied in the keyinfo? true
  Ok
12. Checking that the Site URL Attribute contains a valid site url, if provided
  Not Provided
13. Looking for portal and organization id, if provided
  Not Provided
14. Checking if session security level is valid, if provided
  Ok
Subject: ad46dd87c3c0671a67475e66758ded984c7d3073
Unable to map the subject to a Salesforce.com user

AssertionId: _e871962c45fa10cac5e59e2d14a44fae19936dc95a

can you please check point (6) issue how to solve?
Last recorded SAML login failure:  2015-06-04T04:58:34.395Z
Unexpected Exceptions
  Ok
1. Validating the Status
  Ok
2. Looking for an Authentication Statement
  Ok
3. Looking for a Conditions statement
  Ok
4. Checking that the timestamps in the assertion are valid
  Ok
5. Checking that the Attribute namespace matches, if provided
  Not Provided
6. Miscellaneous format confirmations
  InResponseTo must be empty for Idp-init Browser POST Profile
7. Confirming Issuer matches
  Ok
8. Confirming a Subject Confirmation was provided and contains valid timestamps
  Ok
9. Checking that the Audience matches
  Ok
10. Checking the Recipient
  Ok
  Organization Id that we expected: 00D28000000WHXX
  Organization Id that we found based on your assertion: 00D28000000WHXX
11. Validating the Signature
  Is the response signed? true
  Is the assertion signed? true
  Is the correct certificate supplied in the keyinfo? true
  Ok
12. Checking that the Site URL Attribute contains a valid site url, if provided
  Not Provided
13. Looking for portal and organization id, if provided
  Not Provided
14. Checking if session security level is valid, if provided
  Ok
Subject: ad46dd87c3c0671a67475e66758ded984c7d3073
Unable to map the subject to a Salesforce.com user

AssertionId: _e871962c45fa10cac5e59e2d14a44fae19936dc95a