The entity is not key value coding-compliant for the key

I'm developing a plugin for a OSX software to export datas to a .csv file, there are a few warnings at compilation time, but this error is what caught my attention.

"The entity Study is not key value coding-compliant for the key "database".

http://ift.tt/1LN4Dou

Could someone enlighten me on this ?

I did not post the whole code yet, since I don't really know where the problem occurs.

It might be :

db = [[BrowserController currentBrowser] databaseOutline];
NSManagedObject *aFile = [db itemAtRow: r];
if ( aFile && [[[aFile entity] name] isEqual:&"Study"])

Here is the .h

#import <Foundation/Foundation.h>
#import <HiddenAPI/PluginFilter.h>
#import "CHCSV.h"
#import "CHCSVParser.h"
#import "CHCSVWrtier.h"

@class MyOutlineView;

@interface ExportToCSVFilter : PluginFilter {
    MyOutlineView *db;
    NSUserDefaults *prefs;
}

- (void) chooseDefault;
- (void) exportToCSV;

@end

I'd post the rest when I'll know what may be causing this error.

Thanks!