Apple Mach-O Linker Error (IAP)

I'm struggling with in-app purchases. Whenever I import StoreKit, I receive this error. I've been at this for days with no luck.. Someone help? Header File: ``` #import <StoreKit/StoreKit.h> #define kInAppPurchaseManagerProductsFetchedNotification @"kInAppPurchaseManagerProductsFetchedNotification" @interface InAppPurchaseManager : NSObject <SKProductsRequestDelegate> { SKProduct *proUpgradeProduct; SKProductsRequest *productsRequest; } @end ``` Implementation File: ``` #import "IAPManager.h" @implementation InAppPurchaseManager - (void)requestProUpgradeProductData { NSSet *productIdentifiers = [NSSet setWithObject:@"com.runmonster.runmonsterfree.upgradetopro" ]; productsRequest = [[SKProductsRequest alloc] initWithProductIdentifiers:productIdentifiers]; productsRequest.delegate = self; [productsRequest start]; } #pragma mark - #pragma mark SKProductsRequestDelegate methods - (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response { NSArray *products = response.products; proUpgradeProduct = [products count] == 1 ? [[products firstObject] retain] : nil; if (proUpgradeProduct) { NSLog(@"Product title: %@" , proUpgradeProduct.localizedTitle); NSLog(@"Product description: %@" , proUpgradeProduct.localizedDescription); NSLog(@"Product price: %@" , proUpgradeProduct.price); NSLog(@"Product id: %@" , proUpgradeProduct.productIdentifier); } for (NSString *invalidProductId in response.invalidProductIdentifiers) { NSLog(@"Invalid product id: %@" , invalidProductId); } [productsRequest release]; [[NSNotificationCenter defaultCenter] postNotificationName:kInAppPurchaseManagerProductsFetchedNotification object:self userInfo:nil]; } @end ``` The error thats killing me: ``` Undefined symbols for architecture armv7: "_OBJC_CLASS_$_SKProductsRequest", referenced from: objc-class-ref in IAPManager.o ld: symbol(s) not found for architecture armv7 collect2: ld returned 1 exit status "_OBJC_CLASS_$_SKProductsRequest", referenced from: Objc-class-ref in IAPManager.o Symbol(s) not found for architecture armv7 Collect2: Id returned 1 exit status ```