not all arguments converted during string formatting

[Blues5]

File "tools.py", line 32, in load_model
with open('%s.f8k.npz.dictionary.pkl'%path_to_model, 'rb') as f:
TypeError: not all arguments converted during string formatting

default_model = '/home/koel/workplace/semantic-embedding/vse/f8k.npz'
print 'OK'
#-----------------------------------------------------------------------------#

def load_model(path_to_model=default_model):
"""
Load all model components
"""
print path_to_model

# Load the worddict
print 'Loading dictionary...'
with open('%s.f8k.npz.dictionary.pkl'%path_to_model, 'rb') as f:
    worddict = pkl.load(f)