ติดปัญหา cannot find protocol declaration ใน AppDelegate เป็นเพราะอะไรครับ

Class สร้างเอง

@protocol OSServicesDelegate <NSObject>

-(void)SuccessSoap: (NSMutableArray *)output setTags: (int)tags;
-(void)FailSoap;
@end

@interface OSServices : NSObject<NSURLConnectionDelegate,OSServiceParserDelegate,UIAlertViewDelegate,MBProgressHUDDelegate>
{
id<OSServicesDelegate> delegate;
int setTags;

}
@property(nonatomic,retain) id<OSServicesDelegate> delegate;
@property(nonatomic,assign) int setTags;
-(void)OSServicesCallMethod: (NSMutableArray *)_function tgs: (NSMutableArray *)_tags vrs: (NSMutableArray *)_vars url: (NSString *)_url;
@end

พอนำมาใส่ใน AppDelegate

#import <UIKit/UIKit.h>
#import "MainMenuViewController.h"
#import "MGarage.h"
#import "OSServices.h"

@interface AppDelegate : UIResponder <UIApplicationDelegate,OSServicesDelegate>
{
NSUserDefaults *pref;


}
@property(nonatomic,strong) NSUserDefaults *pref;
@property (strong, nonatomic) UIWindow *window;


@end

มันก็ Error cannot find protocol declaration for OSServicesDelegate มันผิดตรงไหนครับ ???