Given wrong tracking number on dsers app?

[GalaxyRed]

I did a test order on this AliExpress product the problem I had. I was given this tracking number for USPS via dsers it was never updated whatsoever. I then contacted the seller on AliExpress and he gave me a other tracking number which he said it was the correct one. When I checked it on parcelapp It worked. My question is why did dsers give me a USPS tracking number that never worked. While the seller gave me the correct tracking number? I got the product yesterday.

[Anindita]

Hi @GalaxyRed 

Though I am not very much sure about it but since the third party app is involved along with dropshipping, is there some way that two tracking numbers are generated? But I think it will be clear if you contact both the app & the dropshipper company to resolve this.