Can't access to shared folder from Windows 7

I have 3 computers in my network. One computer with shared folder running Windows 8, another computer with Windows 8 and the last with Windows 7.

The two Windows 8 computers can access to the two other computers (Windows 8 and Windows 7).

But the Windows 7 computer can't access to both Windows 8 computers. When I try to access from my Windows 7 computer to Windows 8 computer I get error:

Error code: 0x800704cf
The network location cannot be reached.

But the ping succeed from Windows 7 to Windows 8.

What should I do?

EDIT:
machine status:

• All the machine runs with 64 bit version of Windows.
• The Windows 7 machine have Service Pack 1.
• When I turn off the firewall the error still there.
• File and Printer Sharing is checked in all machines.
• I don't have homegroup and all the computers have the same workgroup name. When I try to access to machine I enter the computer name or IP.
• Network Discovery is ON in all computers.
• Password protected sharing is ON in all computers.
• I have credentials for the others machines in my network.