From `:h :normal`:
{commands} should be a complete command. If
{commands} does not finish a command, the last one
will be aborted as if
To complete a `/pattern` you need to press `Enter`. But when you press `Enter`, you're actually finishing the `:normal` command, so the `/pattern` remains incomplete.
You can include the `Enter` as part of the command by using `Ctrl``V`+`Enter`:
:normal /over^M
Vim will show `Ctrl``V`+`Enter` as `^M`. See `:h c_CTRL-V`.