Cita:
Iniciado por xjuanch0x 
Bueno en cuanto a lo del valor de la base de datos, me da la impresión de que es configuración regional, deberías manejar todos los campos como decimal incluyendo el dato que le envías a tu consulta.
Con lo del objeto, es complicado decir que sucede solo con la descripción que colocas
Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[NullReferenceException: Object reference not set to an instance of an object.]
PageAdmin.EliminaLosCaducado(Int32 idusuario) +1600
PageAdmin.Page_Load(Object sender, EventArgs e) +196
System.Web.Util.CalliHelper.EventArgFunctionCaller (IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Cal lback(Object sender, EventArgs e) +35
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +50
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627