ExpandDims dim value error

[jackpopp125]

My problem is that I give observation sequence 3~5 states, the program can run, but when I give observation sequence 2 states, it raised some errors.

Below is error,

ValueError: dim 1 not in the interval [-1, 0]. for 'Train_Baum_Welch/EM_step-0/Re_estimate_transition/Smooth_gamma/ExpandDims' (op: 'ExpandDims') with input shapes: [], [] and with computed input tensors: input[1] = <1>.

Is it caused by the tensor dimension? Could you please help me to solve the issue? Appreciate for your help.

Warm regards,
Jacky