Error reading bp file

[rkube]

I'm having problems reading data from a file:

ValueError                                Traceback (most recent call last)
<ipython-input-34-81130de3c7ef> in <module>
      1 with adios2.open(join(data_dir, "xgc.3d.00402.bp"), "r") as df:
----> 2     a_par = df.read("a_par")

ValueError: ERROR: offset 0 from steps start 125 in variable a_par is beyond the largest available step = 125, check Variable SetStepSelection argument stepsCount (random access), or number of BeginStep calls (streaming), in call to Get

Looking at bpls, the data should be there:

$ bpls xgc.3d.00402.bp
  double   a_par     {7477, 8}

[rkube]

This error is from reading adios1 files with adios2.