Creating new level with wpf

[tamsann]

Hello, I'm trying to create a new level in Revit API combined with WPF to enter the level's elevation and an OK button. When clicking OK, the new level will be created. but there is some error and I don't know how to fix it, please help me. 

please find the project here

https://www.dropbox.com/scl/fo/ugmne5tpio0840riiz7dg/h?dl=0&rlkey=8afu47mc63mjx5t7f6v4djcc7

Or see the pictures below:

[studio-a-int · Accepted solution]

Your class needs to be derived from Window, not UserControl

public partial class yourClass : System.Windows.Window

[Mohamed_Arshad · Accepted solution]

@tamsann 
Kindly follow the below image instructions to resolve your issue

Hope this will resolve your issue.

[tamsann]

@Mohamed_Arshad @studio-a-int  It's work, Thank you for your supports!!!