CashServer error every 2 min

[viktor145]

Unhandled Exception:

System.InvalidCastException: Cannot cast from source type to destination type.

  at System.DBNull.System.IConvertible.ToInt32 (IFormatProvider provider) [0x00000] in <filename unknown>:0 

  at System.Convert.ToInt32 (System.Object value, IFormatProvider provider) [0x00000] in <filename unknown>:0 

  at System.Convert.ToInt32 (System.Object value) [0x00000] in <filename unknown>:0 

  at Cash_Server.Users.GetCashBalance (System.String username, Int32 userid) [0x00000] in <filename unknown>:0 

  at Cash_Server.Users.ProcessCashBalanceRequest (System.Byte[] packet, Int32 ClientID) [0x00000] in <filename unknown>:0 

  at Cash_Server.NetIO.Incomming (System.Byte[] packet, Int32 ClientID) [0x00000] in <filename unknown>:0 

  at Cash_Server.NetIO.OnDataReceived (IAsyncResult asyn) [0x00000] in <filename unknown>:0