Are you running a domain or is this setup in a workgroup enviroment? There are huge difference on how to do these things depending on what enviroment you are in.
Let me know what your setup is and I will try and assist you.
Please make sure once again by going to that folder and check in sharing tab you will find one button “Permissions”, please click this button apply the permissions here and recheck it will work.
for permission you have to select the user or user group. and after applying this setting you will see that folder on other PC on LAN. be careful to give rights if you don’t select everyone then you can not access that folder and if that PC is not in domain so you have to give extra permission by clicking on advance button in permissions box. if it does not work then you will ask me by mail firstname.lastname@example.org