DBmails are not working after modifying the sp_send_dbmail procedure

I have modified sp_send_dbmail procedure in sql server. Laster mails stopped working. Dbmail is shutting down automatically and getting this error while I restart process >Exception Information ===================\ Exception Type: Microsoft.SqlServer.Management.SqlIMail.Server.Common.BaseException Message: The Transaction not longer valid. \ Data: System.Collections.ListDictionaryInternal TargetSite: Void ValidateConnectionAndTransaction() HelpLink: NULL Source: DatabaseMailEngine HResult: -2146232832 StackTrace Information =================== at Microsoft.SqlServer.Management.SqlIMail.Server.DataAccess.ConnectionManager.ValidateConnectionAndTransaction() at Microsoft.SqlServer.Management.SqlIMail.Server.DataAccess.ConnectionManager.RollbackTransaction() at Microsoft.SqlServer.Management.SqlIMail.IMailProcess.QueueItemProcesser.GetDataFromQueue(DataAccessAdapter da, Int32 lifetimeMinimumSec) at Microsoft.SqlServer.Management.SqlIMail.IMailProcess.QueueItemProcesser.ProcessQueueItems(String dbName, String dbServerName, Int32 lifetimeMinimumSec, LogLevel loggingLevel, Byte[] encryptionKey, Int32 connectionTimeout) Please do help me