c# - Substring error though not using substring -

i have following code:

public static long createvendorsemailjob(list<recipient> recipients, string subject, string body)         {             long emailjobid;              using (var connection = new mysqlconnection(configurationmanager.connectionstrings["myconnection"].connectionstring))             {                 connection.open();                  // create email job                 using (var command = new mysqlcommand())                 {                     command.connection = connection;                     command.commandtype = commandtype.text;                     command.commandtext =                         string.format(                             "insert email_job (parent_id, job_type_lookup_id, from_email, from_name, subject, body_type_lookup_id, body, status_lookup_id, total_emails, persist_addresses) values ({0}, {1}, '{2}', '{3}', '{4}', {5}, '{6}', {7}, {8}, {9})",                             5000,                             745,                             "info@domain.com",                             "company management system",                             subject,                             22,                             body,                             27,                             recipients.count,                             1);                      command.executenonquery();                      emailjobid = command.lastinsertedid;                 }                  using (var command = new mysqlcommand())                 {                     command.connection = connection;                     command.commandtype = commandtype.text;                      string commandtext = "insert email_job_email (job_id, comm_optin_id, name, email) values ";                     var valuestoadd = new list<string>();                      recipients.foreach(r => valuestoadd.add(string.format("({0}, {1}, '{2}', '{3}')", emailjobid, r.recipientid, r.name, r.emailaddress)));                      commandtext += string.join(",", valuestoadd.toarray());                      command.commandtext = commandtext;                     command.executenonquery();                 }                  connection.close();             }              return emailjobid;         } 

this code runs fine when running 1 task run same code task , doesn't work. gives me following error:

index , length must refer location within string. parameter name: length 

now difference between each time run subject , body of message. stored in resource file , passed in when method called. can't seem figure out exception happening. windows service , runs on remote machine debugging not easy , don't have dev environment mirror theirs.

the error have seen before seems sort of substring manipulation. text basic stuff , 1 similar other can't see why causing this.

any ideas on or why?

edit: ok after had aha moment , realized print out stack trace here got -

at mysql.data.mysqlclient.mysqltokenizer.nextparameter()    @ mysql.data.mysqlclient.statement.internalbindparameters(string sql, mysqlparametercollection parameters, mysqlpacket packet)    @ mysql.data.mysqlclient.statement.bindparameters()    @ mysql.data.mysqlclient.preparablestatement.execute()    @ mysql.data.mysqlclient.mysqlcommand.executereader(commandbehavior behavior)    @ mysql.data.mysqlclient.mysqlcommand.executenonquery()    @ pcm.autoworkengine.tasks.recurringvendormailer.entities.datamappers.emailjobmapper.createvendorsemailjob(list`1 recipients, string subject, string body) in c:\projects\pcm\pcm.autoworkengine.recurringvendormailer\entities\datamappers\emailjobmapper.cs:line 65    @ pcm.autoworkengine.tasks.recurringvendormailer.hoavendortask.execute() in c:\projects\pcm\pcm.autoworkengine.recurringvendormailer\hoavendortask.cs:line 24    @ pcm.autoworkengine.autoworkengineservice.start() in c:\projects\pcm\pcm.autoworkengine\autoworkengineservice.cs:line 80  

what not familiar prepared statements mysql. not trying use that. have single quotes in text. have in both texts , work fine in first not sure if it. escape them in resource file using backslash.

you need sanitize subject , body. example if subject

');

you'll run trouble. see example here , here.