GurobiError: Unsupported type (<class 'list'>) for LinExpr addition argument

Hi,

I run 'diet2.py' in Anaconda 4.2.0, Python 3.5.6 and met this problem.

Python 3.5.6 |Anaconda 4.2.0 (64-bit)| (default, Aug 26 2018, 16:05:27) [MSC v.1900 64 bit (AMD64)]

Type "copyright", "credits" or "license" for more information.

IPython 6.2.1 -- An enhanced Interactive Python.

runfile('D:/Program Files/gurobi751/win64/examples/python/diet2.py', wdir='D:/Program Files/gurobi751/win64/examples/python')

Traceback (most recent call last):

  File "<ipython-input-1-2ae817e615ea>", line 1, in <module>

    runfile('D:/Program Files/gurobi751/win64/examples/python/diet2.py', wdir='D:/Program Files/gurobi751/win64/examples/python')

  File "D:\Program Files\Anaconda3\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 678, in runfile

    execfile(filename, namespace)

  File "D:\Program Files\Anaconda3\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 106, in execfile

    exec(compile(f.read(), filename, 'exec'), namespace)

  File "D:/Program Files/gurobi751/win64/examples/python/diet2.py", line 72, in <module>

    foods, cost, nutritionValues)

  File "D:\Program Files\gurobi751\win64\examples\python\dietmodel.py", line 29, in solve

    for c in categories), "_")

  File "model.pxi", line 2552, in gurobipy.Model.addConstrs (../../src/python/gurobipy.c:78637)

  File "model.pxi", line 2464, in gurobipy.Model.addConstr (../../src/python/gurobipy.c:77389)

  File "linexpr.pxi", line 429, in gurobipy.LinExpr.__sub__ (../../src/python/gurobipy.c:32252)

  File "linexpr.pxi", line 408, in gurobipy.LinExpr.__add__ (../../src/python/gurobipy.c:31857)

  File "linexpr.pxi", line 153, in gurobipy.LinExpr.add (../../src/python/gurobipy.c:29245)

GurobiError: Unsupported type (<class 'list'>) for LinExpr addition argument

I had no idea.  A Gurobi provided example should not have a problem like this. Can anyone help me?

Thanks,

Larry