Collection View Controller Error

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Exception: Object reference not set to an instance of an object
  at XamariniOSTest1.ViewController3..ctor (IntPtr handle) [0x00020] in /Users/urielarvizu/Projects/XamarinTest1/XamariniOSTest1/Screens/ViewController3.cs:24
  at at (wrapper managed-to-native) System.Reflection.MonoCMethod:InternalInvoke (System.Reflection.MonoCMethod,object,object[],System.Exception&)
  at System.Reflection.MonoCMethod.InternalInvoke (System.Object obj, System.Object[] parameters) [0x00002] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:537
  --- End of inner exception stack trace ---
  at System.Reflection.MonoCMethod.InternalInvoke (System.Object obj, System.Object[] parameters) [0x00016] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:543
  at System.Reflection.MonoCMethod.DoInvoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00095] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:528
  at System.Reflection.MonoCMethod.Invoke (BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:556
  at System.Reflection.ConstructorInfo.Invoke (System.Object[] parameters) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/ConstructorInfo.cs:62
  at MonoTouch.ObjCRuntime.Runtime.ConstructNSObject[NSObject] (IntPtr ptr, System.Type type, MissingCtorResolution missingCtorResolution) [0x0003e] in /Developer/MonoTouch/Source/maccore/src/ObjCRuntime/Runtime.iOS.cs:419
  at MonoTouch.ObjCRuntime.Runtime.ConstructNSObject (IntPtr ptr, IntPtr klass, MissingCtorResolution missingCtorResolution) [0x00013] in /Developer/MonoTouch/Source/maccore/src/ObjCRuntime/Runtime.iOS.cs:400
  at MonoTouch.ObjCRuntime.Runtime.GetNSObject (IntPtr ptr, MissingCtorResolution missingCtorResolution, Boolean evenInFinalizerQueue) [0x00022] in /Developer/MonoTouch/Source/maccore/src/ObjCRuntime/Runtime.iOS.cs:490
  at MonoTouch.Registrar.DynamicRegistrar.GetMethodDescriptionAndObject (System.Type type, IntPtr selector, IntPtr obj, Boolean throw_on_failure, System.IntPtr& mthis) [0x00043] in /Developer/MonoTouch/Source/maccore/src/ObjCRuntime/DynamicRegistrar.cs:620
  at MonoTouch.ObjCRuntime.Runtime.GetMethodAndObject (IntPtr klass, IntPtr sel, IntPtr obj, Boolean throw_on_failure, System.IntPtr& mthis) [0x00000] in /Developer/MonoTouch/Source/maccore/src/ObjCRuntime/Runtime.iOS.cs:230
  at at (wrapper native-to-managed) MonoTouch.ObjCRuntime.Runtime:GetMethodAndObject (intptr,intptr,intptr,int,intptr&)
  at at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication:UIApplicationMain (int,string[],intptr,intptr)
  at MonoTouch.UIKit.UIApplication.Main (System.String[] args, IntPtr principal, IntPtr delegate) [0x00005] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:62
  at MonoTouch.UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x00038] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:46
  at XamariniOSTest1.Application.Main (System.String[] args) [0x00008] in /Users/urielarvizu/Projects/XamarinTest1/XamariniOSTest1/Main.cs:17