text: Title:  I am training with my own data set, but the problem of loss is empty.
  Body: my pc 
  GTX1080Ti  centos7   learnng rate 1e-5
  Who has the same situation as me, please help me. thanks。
   iter 310 || Loss: nan || timer: 0.1921 sec.
  iter 320 || Loss: nan || timer: 0.2041 sec.
  iter 330 || Loss: nan || timer: 0.2006 sec.
  iter 340 || Loss: nan || timer: 0.2043 sec.
  iter 350 || Loss: nan || timer: 0.2128 sec.
  iter 360 || Loss: nan || timer: 0.2072 sec.
  iter 370 || Loss: nan || timer: 0.2091 sec.
  iter 380 || Loss: nan || timer: 0.2141 sec.
  iter 390 || Loss: nan || timer: 0.2486 sec.
  iter 400 || Loss: nan || timer: 0.1914 sec.
  iter 410 || Loss: nan || timer: 0.2052 sec.
  iter 420 || Loss: nan || timer: 0.1976 sec.
  iter 430 || Loss: nan || timer: 0.1952 sec.
  iter 440 || Loss: nan || timer: 0.1942 sec.
  iter 450 || Loss: nan || timer: 0.2101 sec.
  iter 460 || Loss: nan || timer: 0.1934 sec.