On my ubuntu this line works
You also need dialog installed.
I have to change the geometry to correct size. Oversize it first like 80x25, and then decrease to correct size.
And your "-1 16" at the end I don't know that stands for.
xterm +sb -title "Calendar" -geometry 40x19 -e dialog --no-cancel --ok-label " CLOSE " --no-shadow --calendar "" 0 0