[lake_example] ** ERROR OPENING FILE "lake_example.hds" ON UNIT

I'm new to MODFLOW. I installed MODFLOW-2005 and flopy 3.2.4 in my mac and tried to run the lake_example in my ipython notebook.

It complained with the following error when it tried to run the model by (m1.run_model):

FloPy is using the following executable to run the model: /Users/Ben1897/Documents/research/code/mf2005v1_11_00_unix/src/mf2005

                              MODFLOW-2005     
U.S. GEOLOGICAL SURVEY MODULAR FINITE-DIFFERENCE GROUND-WATER FLOW MODEL
                         Version 1.11.00 8/8/2013

Using NAME file: lake_example.nam Run start date and time (yyyy/mm/dd hh:mm:ss): 2016/03/16 17:11:31

*\ ERROR OPENING FILE "lake_example.hds" ON UNIT 51 SPECIFIED FILE STATUS: REPLACE SPECIFIED FILE FORMAT: BINARY
SPECIFIED FILE ACCESS: SEQUENTIAL
SPECIFIED FILE ACTION: READWRITE
-- STOP EXECUTION (SGWF2BAS7OPEN)

Actually, a similar error occurs when I run the tutorial 1 example.

mf2005 should be installed successfully in my mac for the test problems pass.

Thanks in advance!

modflowpy / flopy

[lake_example] ** ERROR OPENING FILE "lake_example.hds" ON UNIT #102