This has worked in the past, but haven't actually deployed in a while.. and now TeamCity is complaining..
[14:02:23][Step 3/6] Invalid source argument:
[14:02:23][Step 3/6] Could not interpret 'C:\\TeamCity\\buildAgent\\work\\92cb0b109899efe9\\trunk\\source\\My.Database' as a valid source.
[14:02:23][Step 3/6] Process exited with code 1
[14:02:23][Step 3/6] Step Deploy My.Database (Command Line) failed
Which version of RGPublish are you using? Can you try appending /verbose to the command to see if it logs more information?
Out of curiosity I tried packaging a folder with a period in the name using RGPublish and it was fine - although /Configuration isn't a switch I recognise, and my version certainly complained about it being there.