Null value

Question

Hi everybody,

 

I have this:

 

[code]

 

if (medicijn.Volgorde == 999)

{

int medicijnHigest = medicijnService.GetAll().Where(i => i.Volgorde != 999).Max(m => m.Volgorde);

medicijn.Volgorde = medicijnHigest + 1;

medicijnService.Save(medicijn);

}

[/code] 

 

but I get this error on  medicijnHigest:

 

 

 

An exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll but was not handled in user code

Additional information: The cast to value type 'System.Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.

 

Thank you