Error in Fetching Data From Another Application - In Zoho Creator

I have written function in Application 1 to fetch Data from Application 2. The data passed and returned are in map format.

i) I always get null values from Application 2 though the script and data passed from Application 1 are accurate.
ii) But when the function in Application 2 Executed directly it gives correct values.

App 1 Function:

void retrive_from_Apptwo.retrive_information(int uniqueID)
{
          product_information = Map();
          product_information.put("UniqueID", uniqueID);
          product_response=Map();
          product_response=Application_two.retrive_product.product_details(product_information);

      info product_response;
}

App 2 Function:

map retrive_product.product_details_fetch(map productID)
{
    unique_id = productID.get("UniqueID");
    product_map = Map();
     if(unique_id != null)
       {
            info unique_id;
            product_info_record = new_product_details [ ID == unique_id.toLong() ];
                  if(product_info_record.ID!=null)
                  {
                    product_map.put("Product Name", product_info_record.Product_Name);
                }
        }
    return product_map ;
}

Any Ideas?