renaming with variable at end

[j99mac]

I am trying to add a variable at the end of my file when renaming.
This is what I am adding at the end of my command
_s_'ts'.%e'

when I run it nothing happens and the files do not get renamed.
The variable is $ts. where the user enters input

[Phil Harvey]

What is your full command?  What O/S are you running?  How are you running the command (from what shell or what type of script or program)?

- Phil