Cannot pass image url from flow to people in custom function

Cannot pass image url from flow to people in custom function

I receive this error each time I try to pass the Image URL to an image field in Zoho people via this custom fucntion:
CUSTOM FUNCTION (hidden Image URL in post here):
  1. string test_vishal(string test_input)
    {
    file_object = invokeurl
    [
    url :"https://xxxxxxx.com/rdex-security-services-nj-logo.png"
    type :GET
    ];
    param_map = Map();
    param_map.put("Drivers_License_Photo","file_object");
    param_map.put("recordid","669115000000223001");
    response = zoho.people.update("employee",param_map);
    return response.toString();
    }

ERROR:
  1. {
	"response": {
		"message": "Error occurred",
		"uri": "/api/forms/json/employee/updateRecord",
		"errors": {
			"code": 7400,
			"message": "Sorry! Server error occurred."
		},
		"status": 1
	} 
    }​