The query contained only ignored words OleDbException using Index Server

I have ASP.NET 4.6.1 WebForms Legacy that using Index Server in Windows Server 2008 R2.

I get OleDbException error with message:

The query contained only ignored words.

My code:

 var datos = new List<Documento>();
 var sql = "Select DocAuthor, vpath, doctitle, FileName, Path, Write, Size, Rank, Create, Characterization, DocCategory from " + Settings.Default.NombreCatalogoIndexServer + "..Scope() where " + FunctionContains(texto) + " order by rank desc";

            using (var da = new OleDbDataAdapter(sql, "Provider=MSIDXS;"))
            {
                using (var testDataSet = new DataSet())
                {
                    da.Fill(testDataSet, "SearchResults");
                    using (var catalogo = testDataSet.Tables[0])

Full error:

System.Data.OleDb.OleDbException (0x80041605):

The query contained only ignored words.

at System.Data.OleDb.OleDbCommand.ExecuteCommandTextErrorHandling(OleDbHResult hr) at System.Data.OleDb.OleDbCommand.ExecuteCommandTextForSingleResult(tagDBPARAMS dbParams, Object& executeResult) at System.Data.OleDb.OleDbCommand.ExecuteCommandText(Object& executeResult) at System.Data.OleDb.OleDbCommand.ExecuteReaderInternal(CommandBehavior behavior, String method) at System.Data.OleDb.OleDbCommand.ExecuteReader(CommandBehavior behavior) at System.Data.OleDb.OleDbCommand.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior) at System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable)

Keys:

1. How can I remove all noise ?
2. How can I configure Index Server for Spanish culture ?

Any suggestions ?