error CS0738 Interface implementation - c#-4.0

Question

I have the following interface:
public delegate void NotifyOnModulesAvailabilityHandler(Lazy[] modules);
public interface IModulesLoader
{
event NotifyOnModulesAvailabilityHandler NotifyOnModulesAvailability;
Lazy<UserControl, IModuleMetadata>[] Modules { get; set; }
void OnImportsSatisfied();
}
I'm tring to implement this interface like this:
public class ModulesLoader : IModulesLoader, IPartImportsSatisfiedNotification
{
#region Events
public event NotifyOnModulesAvailabilityHandler NotifyOnModulesAvailability;
#endregion
#region Public Contructor
public ModulesLoader()
{
DeploymentCatalogService.Instance.Initialize();
CompositionInitializer.SatisfyImports(this);
this.LoadModules();
}
#endregion
#region Properties
[ImportMany(AllowRecomposition = true)]
public Lazy<UserControl, IModuleMetadata>[] Modules
{
get;
set;
}
#endregion
#region IPartImportsSatisfiedNotification Members
public void OnImportsSatisfied()
{
var handler = this.NotifyOnModulesAvailability;
if (handler != null)
{
handler(this.Modules);
}
}
#endregion
#region Private Methods
private void LoadModules()
{
var wc = new WebClient();
wc.OpenReadCompleted += (s, e) =>
{
var streamInfo = e.Result;
var xElement = XElement.Load(streamInfo);
var modulesList = from m in xElement.Elements("ModuleInfo")
select m;
if (modulesList.Any())
{
foreach (var module in modulesList)
{
var moduleName = module.Attribute("XapFilename").Value;
DeploymentCatalogService.Instance.AddXap(moduleName);
}
}
};
wc.OpenReadAsync(new Uri("ModulesCatalog.xml", UriKind.Relative));
}
#endregion
}
I get the following error:
Error 1 'TunisiaMeeting.Extensibility.Shell.Helpers.Deployment.ModulesLoader' does not implement interface member 'TunisiaMeeting.MefBase.Interfaces.IModulesLoader.Modules'. 'TunisiaMeeting.Extensibility.Shell.Helpers.Deployment.ModulesLoader.Modules' cannot implement 'TunisiaMeeting.MefBase.Interfaces.IModulesLoader.Modules' because it does not have the matching return type of 'System.Lazy``2<System.Windows.Controls.UserControl,TunisiaMeeting.MefBase.Interfaces.IModuleMetadata>[]'. C:\Imed\TunisiaMeeting\TunisiaMeeting.Extensibility.Shell\Helpers\Deployment\ModulesLoader.cs 18 18 TunisiaMeeting.Extensibility.Shell
I'm pretty sure I have the same return Type Lazy<UserControl, IModuleMetadata>[] in both my class and my interface for my property.
Any Help please ?
Thank you all

Answer 1

You haven't shown where UserControl and IModuleMetadata come from... my guess is that your interface is referring to one pair of types whereas your implementation is referring to a different pair:
Make sure they're referring to the same types in the same namespaces
Make sure you only have one copy of each type (e.g. that you haven't got one copy in a class library, and redeclared it somewhere else)