Why tcpdump get nothing when music is playing on my local apache?

No wireline connects to net for my local pc.
Apache2 was installed and a music was put on /var/www/html/test.ogg.
It can be played with chrome 127.0.0.1/test.ogg.
tcpdump was running when playing the music----test.ogg with chrome.

sudo tcpdump tcp port 80  -i lo -vv
tcpdump: listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes

Why the command get nothing excepttcpdump: listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes?

Solution

You should check the following:

Is chrome cache cleared?
What is the response code in chrome - it should be 200 OK.
Chrome is making a connection on 127.0.0.1:some_ephemeral_port -- to apache:127.0.0.1:80 - make sure it is 80, not 443!
Start the capture before opening the file (when did you start the capture)?
In case nothing helps try, sudo tcpdump -i any -vv port 80 (if you are sure of the port).
Try capturing other requests - like the apache home page and see if that works.