UiPath Activity Creator Issues

Hello everyone, i am a beginner on creating an activity package with UiPath Activity Creator.

I need help regarding :

  1. I am getting UI related issue, that the activity(Parent Scope Activity) is not visible, and getting below errors(Image 1 for : While dragging into sequence and Image 2 for : when the activity is in sequence).

Image 1 :

Image 2 :

I changed parent and child activity names according to my need in Product.Activities package(haven’t touched Designer part yet). And not getting any error while building package.
Can anybody suggest, what i am doing wrong?

  1. While debugging above parent activity, getting below error :

Code for ExecuteAsync method of parent scope is :

Below lines are generating this issue :

var property = context.DataContext.GetProperties()[RemScope.ApplicationTag];
var app = property.GetValue(context.DataContext) as RemSession;

I don’t know what i am doing wrong. Maybe the context is empty.
Please tell me where i am wrong.

  1. I have a password field and i want it to be hidden(Like a password field looks).
    I tried :
    [DataType(DataType.Password)] (with using System.ComponentModel.DataAnnotations;) and
    Both of these not worked.

How i can secure that field?

Also, i cannot find any good documentation or tutorial specific to UiPath Activity creator. Just have WPF tutorials. Apart from quick start and Anatomy of an Activty, do we have any tutorials available?