Convert from RenderTexture to PNG / JPG...

Hello again,
I want save token pictures as imagefile locally.
My pictures are RenderTextures (Scene Capture Component 2D). So I want convert it in Texture2D and then in PNG and so on…
This is the most used solution from google.
But now I want write it as BP-Library.

My Problem:

voidConvertRenderTextureToTexture2D(UTextureRenderTarget RT);

doesn’t work. Why?
Error: not enough arguments by funtioncall
error is by GENERATED_UCLASS_BODY()

Please help…

Best regards