Unable to process your request. Please verify if the name and value is appropriate for the "xmlData" parameter || 4600

Unable to process your request. Please verify if the name and value is appropriate for the "xmlData" parameter || 4600

Hi,

I'm trying to use the example of insertRecords Method for new contact, using POST.

https://crm.zoho.com/crm/private/xml/Contacts/insertRecords?authtoken=my_xxxToken&scope=crmapi
&newFormat=1
&xmlData=

<Contacts>
<row no="1">
<FL val="First Name">Scott</FL>
<FL val="Last Name">James</FL>
<FL val="Email">test@test.com</FL>
<FL val="Department">CG</FL>
<FL val="Phone">999999999</FL>
<FL val="Fax">99999999</FL>
<FL val="Mobile">99989989</FL>
<FL val="Assistant">John</FL>
</row>
</Contacts>

and I get this response (using postman) - 

could not get any response.

But, if I send this - 

https://crm.zoho.com/crm/private/xml/Accounts/insertRecords?authtoken=xxxxxx&scope=crmapi
&newFormat=1
&xmlData=

the response is ZOHO error message -

<?xml version="1.0" encoding="UTF-8" ?>

<response uri="/crm/private/xml/Contacts/insertRecords">

    <error>  <code>4600</code>

        <message>Unable to process your request. Please verify if the name and value is appropriate for the "xmlData" parameter.</message>

    </error>

</response>

Am I missing something?