http://track-chinapost.com/startairmail.php shows multiple "sent to airlines":

2018-02-09 10:36:33.0 Shanghai center export customs cleared
2018-02-09 20:05:57.0 arrive Shanghai Int'l Airport center
2018-02-10 06:21:39.0 sent to airline
2018-02-12 03:00:00.0 sent to airline
2018-02-20 11:44:00.0 sent to airline
2018-02-20 17:37:00.0 sent to airline

This usually happens when there is limited shipping space to the destination country, and China Post has to try several times to send your parcel out of China. It's not unusual to see this happen. At some point the "sent to airline" messages will stop, and there will be a long time with no updates, which means your item left China successfully.

Unfortunately shipping to Mexico seems very slow lately, often 50-90 days. You'll want to keep checking on your parcel's status. Once it reaches Mexico, it should start updating again.

Can you tell me where my package is please? Number LX753130752CN. Thank you

Quote from sholly on March 2, 2018, 19:33
Can you tell me where my package is please? Number LX753130752CN. Thank you

http://track-chinapost.com/startems.php?code=LX753130752CN shows "No shipping record". Nothing has been sent using this tracking number yet.

Once the parcel is actually sent, the tracking number will start working within 48 hours. If it's been longer than 3-4 days, ask your seller when they are going to send it. If they keep delaying, open a dispute.

Why tracking results shows ” invalid” or “China Post has not received the parcel”?

What does....

“Arrival at inward office of exchange
SYDNEY EMS”

Mean ?

Quote from shene on March 3, 2018, 16:23
where is my package. it was sent to china from jamaica on november 23,2017. however it still had not been delivered and there are no updates on where it is. the tracking number isCP003201355JM

If it hasn't arrived yet it is almost certainly lost. If you contact the post office in Jamaica with your tracking number they might be able to trace its whereabouts for you.