PERT/CPM network and critical path.

This is a re-post for a problem.  I'm confused with the OTA's answer because in the response that I received (attached as 44279-business-CPM, PERT(1).xls), Activity F follows C and D, but in the problem definition, it is supposed to follow A and C.  Please help me clarify this...

I have also attached what I came up with for the model (attached as file MyModel.xls)

Here is the original problem:

Organizers for a political convention have determined ten activities that must be done before the convention begins.

Activity Immediate Predecessors Time (Weeks)
A                       ---                   10
B                        A                     4
C                        B                     2
D                        B                     2
E                         A                     6
F                         A, C                 3
G                         D                    4
H                         F, G                 6
I                         D                      5
J                          E                     4


Please clarify the following:
a.  Draw out the PERT/CPM network for the project.
b.  Identify the critical path.  
c.  Determine how many weeks prior to the convention the work must begin.


Thank you in advance.

Attached file(s):

44279-business-CPM, PERT(1).xls  View File

My model.xls  View File