Using ZDK.HTTP.Request /First argument must be a String / Whats a Wrong?

Using ZDK.HTTP.Request /First argument must be a String / Whats a Wrong?

Hi Team

   Here again with a little problem using ZDK.HTTP.Request, i  need to make a http request from client script, my source code is the following:

  2. filtro = 'DocumentNumber eq ';
  3. filtro = filtro + '\'844989539\'';
  4. filtro = filtro + 'and DocumentType eq ';
  5. filtro = filtro + '\'NationalId\'';
  6. filtro = filtro + 'and DocumentCountry eq ';
  7. filtro = filtro + '\'CL\'';
  8. filtro = '=' + filtro;
  9. ZDK.Client.showMessage(filtro);

  11. kk=ZDK.HTTP.request({
  12.  url: 'https://proxy1.qa.sked24api.io/v1/Patients',
  13.  method: 'GET',
  14.  parameters: {
  15.    $filter: filtro ,
  16.  },
  17.     headers: {
  18.         'Authorization': 'Bearer XXXXXXXXXX',
  19.         'Ocp-Apim-Subscription-Key': 'XXXXXXXXXXX'
  20.     }
  21.  }
  22. );
When i try to run code i get the message:

First argument must be a String

What happens with the code?, can you get me a hand for to solve it?

Thanks in advance
Pablo