I am developing a winform fingerprint reader application using ZKFinger SDK.  

When i am running following code: 

```
ZKFPEngXClass obj = new ZKFPEngXClass();
obj.OnImageReceived += Obj_OnImageReceived;
obj.OnCapture += Obj_OnCapture;
obj.OnEnroll += Obj_OnEnroll;
obj.OnFeatureInfo += Obj_OnFeatureInfo;

```

then i get error on

```
 obj.OnCapture += Obj_OnCapture;
 obj.OnEnroll += Obj_OnEnroll;
 obj.OnFeatureInfo += Obj_OnFeatureInfo;

```

but 

```
obj.OnImageReceived += Obj_OnImageReceived;

```

works fine.

Error is 

> 
> An unhandled exception of type
>  'System.Runtime.InteropServices.COMException' occurred in
>  Interop.ZKFPEngXControl.dll".  
>  Additional information: Exception
>  from HRESULT: 0x80040202
> 
> 
>