android - ActiveAndroid error Failed to Read Row 0, Column -1 from a CursorWindow? -

i trying query database tree objects error thrown: failed read row 0, column -1 cursorwindow has 1021 rows, 15 columns.

model:

@table(name = "treedetails") public class tree extends model {      public tree(){         //mandatory empty constructor         super();     }      @column(name = "scientificname")     public string scientificname;     public string getscientificname() {         return scientificname;     }      public static list<tree> getall(){         return new select()                 .from(tree.class)                 .orderby("scientificname asc")                 .execute();     } } 

in fragment:

public void gettrees(){         log.e(tag, "get trees");          list<tree> trees = tree.getall();     } 

why getting error. there 15 columns in db need 1. spelling of column scientificname.