Why animation in widget doesn't play after changing parent?

I have a widget with my HUD,where i try to repeat menu from Plants vs Zombie 2,when player choose plants to play.

Sunflower_Button is a UserWidget with one button and additional parameters.After click on this button i check,if Game already started or not,if not - i call an event MoveButton,that move button to Named Slot at left side.

In HUD widget i bind event to move function

This function goes threw array of Named Slots,check if they have any children,if not - remove it from currient Named Slot and add it to first free slot at left side.

And when it added to left panel click will execute function to get button back.

Blue second button in test purporses just call animate for first button
And it works if i don’t change parent for my Plant button,after moving it to left panel,animation became broken.

As i see,all breaks when i call add child,but don’t know why and how i can fix it

also if a change set child function to Set content,animation breaks(((((