when i ran code bellow ~

with model:
step1 = pm.Metropolis(vars=[p, sds, centers])
step2 = pm.ElemwiseCategorical(vars=[assignment])
trace = pm.sample(25000, step=[step1, step2])

show error message:
TypeError: Unknown parameter type: <class 'theano.tensor.var.TensorVariable'>

Can anyone tell me what's happen? I had not change any code, just ran it。
I used pymc3。
Thanks!