c# - "Store update, insert, or delete statement affected an unexpected number of rows (0) -

i'm using ef in order insert simple object db:

public bool addquestion(question question) {     try     {         _ctx.questions.add(question);          _ctx.savechanges();         return true;     }     catch(exception ex)     {         return false;     } } 

my dbcontext like:

 public class anycontext:dbcontext  {     public anycontext():base()     {         configuration.proxycreationenabled = false;         configuration.lazyloadingenabled = false;          database.setinitializer(new migratedatabasetolatestversion<anycontext, anycontextmigrationconfiguration>());     }     public anycontext(string connectionstring)         : base(connectionstring)     {          configuration.proxycreationenabled = false;          configuration.lazyloadingenabled = false;           database.setinitializer(new migratedatabasetolatestversion<anycontext, anycontextmigrationconfiguration>());     }      public dbset<question> questions { get; set; }  } 

and poco like:

[table("questions")] public class question {     public int id  { get; set; }     public string body { get; set; }     public string img_path { get; set; }     public int location { get; set; }     public int status { get; set; }     public datetime ask_date { get; set; }  } 

and *"store update, insert, or delete statement affected unexpected number of rows (0). * every time

what doing wrong?