Vuforia Initialization Error

Hello,

I completed development in the past (Unity1.2f + Vuforia 7.6.12 + Hololens) about one month ago.

There was no problem.

but when i excute app at yesterday, even though it was excuted, an error emerged.

The error messages are written in the Hololens screen center. 

                    Vuforia Initialization Error.

                    Failed to initialize Vuforia.

What the....

I never did anything. It was only execution.

I am a VIP member. Maybe there is a license issue?

I would appreciate any help.

Thanks!