Accounts/getRelatedRecords with parentModule=Vendor Unable to populate data

My client is using Vendors as Affiliate Partners and Accounts are associated with 1 Affiliate Partner. Using the Affiliate Partner info I am trying to get related Accounts.

This:

https://crm.zoho.com/crm/private/xml/Vendors/getSearchRecordsByPDC?authtoken=xxxxx&scope=crmapi&version=2&selectColumns(All)&searchColumn=email&searchValue=fxx@hxx.com

yields:

  <response uri="/crm/private/xml/Vendors/getSearchRecordsByPDC">
 

     
     <result>
    
        <Vendors>
       
           <row no="1">
          
            <FL val="VENDORID">
            1820217000002700023
            </FL>
           
              <FL val="Vendor Name">
             
               <![CDATA[ xxx xxx ]]>
              
              </FL>
             
              <FL val="Email">
             
               <![CDATA[ fxxx@xxxx.com ]]>
              
              </FL>
             
            <FL val="SMOWNERID">
            1820217000000118001
            </FL>
           
              <FL val="Vendor Owner">
             
               <![CDATA[ xxx xxx ]]>
              
              </FL>
             
              <FL val="Created Time">
             
               <![CDATA[ 2017-02-06 13:50:03 ]]>
              
              </FL>
             
              <FL val="Modified Time">
             
               <![CDATA[ 2017-02-06 13:50:03 ]]>
              
              </FL>
             
           </row>
          
        </Vendors>
       
     </result>

  </response>
 

 But this:

https://crm.zoho.com/crm/private/xml/Accounts/getRelatedRecords?authtoken=xxxx&scope-crmapi&id=1820217000002700023&parentModule=Vendors

 yields:

 
    <response uri="/crm/private/xml/Accounts/getRelatedRecords">
   
       <error>
      
        <code>
        4401
        </code>
       
          <message>
         
          Unable to populate data, please check if mandatory value is entered correctly.
         
          </message>
         
       </error>
      
    </response>