安装object detection API出错

Traceback (most recent call last):
File "object_detection/builders/model_builder_test.py", line 23, in <module>
from object_detection.builders import model_builder
File "/home/ghf/anaconda2/envs/tensorflow/lib/python2.7/site-packages/tensorflow/models/research/object_detection/builders/model_builder.py", line 22, in <module>
from object_detection.builders import box_predictor_builder
File "/home/ghf/anaconda2/envs/tensorflow/lib/python2.7/site-packages/tensorflow/models/research/object_detection/builders/box_predictor_builder.py", line 21, in <module>
from object_detection.predictors import convolutional_box_predictor
File "/home/ghf/anaconda2/envs/tensorflow/lib/python2.7/site-packages/tensorflow/models/research/object_detection/predictors/convolutional_box_predictor.py", line 19, in <module>
from object_detection.core import box_predictor
File "/home/ghf/anaconda2/envs/tensorflow/lib/python2.7/site-packages/tensorflow/models/research/object_detection/core/box_predictor.py", line 137, in <module>
class KerasBoxPredictor(tf.keras.Model):
AttributeError: 'module' object has no attribute 'Model'
求大神指点