Unreal Engine 4-27 Timeline paused??#[UE4-27]

Hey everyone.I am doing the same thing as this tutorial shows me:Ue4 Tutorial - Moving an Object along a path using a Spline Track - YouTube
But it turned out timeline paused.

I find if i cut custom event out then timeline will be fine.

I just dont know what to do now.Can anybody help me please

Instead of using ‘play’, use ‘play from start’.