Invoice API search customer

When trying to find a specific customer through the API by using

https://invoice.zoho.com/api/search/customers/?authtoken=ec3e4dxxxxxxxxxxxxxxxxx&scope=invoiceapi&apikey=b77ebxxxxxxxxxxxx&searchtext=brocom

it produces the following error:

       <Response status="0">
      
        <Code>
        5
        </Code>
       
          <Message>
         
           <![CDATA[ Invalid URL Passed ]]>
          
          </Message>
         
       </Response>
      
       What am I doing wrong ?