SSMS in Win8 Cannot detect another server in Win7 on LAN

Hi, i am developing a program with vb.net. I have a problem when connected program to database (SQL server). My problem like this :
I have 3 pc. PC-A, PC-B and PC-C. 3 pc is connected in LAN.
OS PC-A & PC-B is win7 sp1 32bit. OS PC-C is win8 64bit.
I install SQL server 2012 SP1 express edition with Advanced service [32 bit] on PC-A.  In PC-C, i install SQL Server 2012 SP1 express edition with Advanced service [64 bit]. In PC-B, i don't install SQL Server.
My program can connect database on PC-A from PC-A and PC-B with connection string like this "Server=192.168.1.201\SQLEXPRESS;Initial Catalog=<my database name>;User ID=<my sql id>;Password=<my pass>"
When i run my program in PC-C to connect database on PC-A, i get error 26 (about server not found).
Then, i try to open SSMS in PC-C. On windows "Connect to Server", i choose Browse for Servers then click tab Network Servers. Th ...