Client script error on searchByCriteria()

Client script error on searchByCriteria()

The error message for this code is:

<!doctype html><html lang="en"><head><title>HTTP Status 400 – Bad Request.....etc..

product_id is correct.
module api name is correct.
  1. product_id = reservations[i].Product_Lookup_Id.trim();
  2. log(product_id);
  3. var ledger_entries_for_product = ZDK.Apps.CRM.Size_Run_Ledgers.searchByCriteria("Product_ID:equals:${product_id}");