Error in executing zoho.books.getRecords

Error in executing zoho.books.getRecords

Hi - I have been using the following code for few months

  aWhere = "invoice_number=" + input.invoice;
// Obtenemos el registro de la factura
booksResults = zoho.books.getRecords("Invoices", "999999999", aWhere);

Note:  999999999 is replaced for real value of my organization.

// Obtenemos los datos propios de la factura
invoiceMap = (booksResults.get("invoices")).toMap();

Today, i am now getting the following error;

Error details:
 Error in executing On User Input script of Factura
 Error.
 Error in executing Set Variable task. Unable to update template varialbe booksResults. 
 Error evaluating MAP expression :
 Error in executing zoho.books.getRecrodsByID task : Error..

Whats happening - any ideas?