Incompatible shapes

hi，excuse me, I encountered the following problems while training the network, may I ask for some assistants?

Traceback (most recent call last):
File "/home/vivian/anaconda3/lib/python3.5/site-packages/tensorflow/python/client/session.py", line 1323, in _do_call
return fn(*args)
File "/home/vivian/anaconda3/lib/python3.5/site-packages/tensorflow/python/client/session.py", line 1302, in _run_fn
status, run_metadata)
File "/home/vivian/anaconda3/lib/python3.5/site-packages/tensorflow/python/framework/errors_impl.py", line 473, in __exit__
c_api.TF_GetCode(self.status.status))
tensorflow.python.framework.errors_impl.InvalidArgumentError: Incompatible shapes: [256,2,4] vs. [2688,2,4]
[[Node: build_loss/FastRCNN_loss/sub = Sub[T=DT_FLOAT, _device="/job:localhost/replica:0/task:0/device:GPU:0"](build_loss/FastRCNN_loss/Reshape, build_loss/FastRCNN_loss/Reshape_1)]]