Adding web config settings programmatically(sharepoint)

Question

Hey... I want to add web config settings from code. I wrote in c# and here is my code:

  SPWebConfigModification bindingsModification = new SPWebConfigModification();           
            bindingsModification.Path = "configuration/system.serviceModel";           
            bindingsModification.Name = "bindings";            
            bindingsModification.Owner = WebConfigModificationOwnerName;             
            bindingsModification.Type = SPWebConfigModification.SPWebConfigModificationType.EnsureChildNode;             
            bindingsModification.Value = bindingConfiguration;              
            webApp.WebConfigModifications.Add(bindingsModification);             
            webApp.WebService.ApplyWebConfigModifications();

but I'm keep getting this error message " 'closeTimeout' is an unexpected token. Expecting white space. Line 1, position 139." ...