Allen-Bradley PanelView Modbus

I'm trying to build a project on PanelView C600 Touch Screen HMI. communicating it using Modbus with a PC via serial link. the PC act as a Modbus slave. after configuring both the slave simulating program and the HMI communication settings, I add a pushbutton command to the screen and linked it to a certain signal. when I run the project and press that command, the value of the register changed on the PC, but I got an error on the HMI saying "Write Error for Alias l63, Controller PLC-1, Address is 00001, Communication Flag is 0". Looking at the messages, it seems like the pc receiving the message and send its response to HMI but the HMI (master) couldn't receive or read the message, same thing happened with reading and writing all other data types.

Hope any one can help solving this issue.
Thanks in advance.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/2711p-um002_-en-p.pdf
"PanelView Component/800: Write/Read Error for Alias xxx, Controller yyy, Address is zzz, Communication Flag is 0 ... This error can occur on a particular screen if the screen objects reference PLC data table areas which are not created, or some are created but not enough elements to cater for all the tag references."

What software simulation are you running on the PC to mimic the Modbus Slave?
Have you tried another software package?

Here are some other packages that you may want to try.
http://www.simplymodbus.ca/download.htm
https://sourceforge.net/projects/easymodbustcp/

Hope this helps you out.
Regards,