Button click event doesn’t work properly

This following code handle button click event. When the user click first time it sets the lable as “First Time”, and when the user click second time it sets the lable as “Second Time”. But it doesn’t work properly. When I first click it, it sets the lable as “First time”, which is correct, but when I click second time, nothing happend.

ASP.NET Identity remove column from AspNetUsers table

When I use ASP.NET Identity first code approach, I want to generate columns in AspNetUsers table in my own way. I don’t need to have stored multiple columns with null values. I just need columns Id, SecurityStamp and UserName.
Only post, that I’ve found is here: AspNet Identity 2.0 Email and UserName duplication , but it is still unsloved (due to error in Santosh comment).