msyukrie, if you can open a working object of the SE application, then you will be able to see the correct syntax for the tags (the same if you open the HMI tags and look inside working tags)
Syntax, as you should have seen from the manual, would be something like:
[shortcut]YourTag - inside an HMI tag
{[shortcut]YourTag1} - if using Direct Reference tag
So, again, try to duplicate a working tag and just change the tag name to the desidered one.
Suggestion from chavak could work fine, but you have to remove the MOV instruction from the RS5000 project, otherwise the value you write from the HMI get overwritten from the PLC's code.
Suggestion from brendan.buchan could work fine,too, but you've to change the Source field of the MOV instruction to be the same tag you've used in the HMI (or you can use the tag named "a" instead, as it is already there in the code)
Hope this helps,
- fuzzy logic