Unsuccessful delivery. The tracking number is RE877416465GR. Please help me as soon as possible. thank you

I had sent a parcel from Greece to China. Final destination is Shenzhen. The whole address specially is 8A2, bu xin da sha, Dong Xiao Road, Luohu district, Shenzhen city, Guang Dong, China
postal code:518000. Today I received a notice Unsuccessful delivery. Could you tell me why ?