Hi Mostafa,
You'll need to add the LS Retail dependency in the app.json file like below:
"dependencies": [
{
"id": "63ca2fa4-4f03-4f2b-a480-172fef340d3f",
"publisher": "Microsoft",
"name": "System Application",
"version": "16.0.0.0"
},
{
"id": "437dbf0e-84ff-417a-965d-ed2bb9650972",
"publisher": "Microsoft",
"name": "Base Application",
"version": "16.0.0.0"
},
{
"id": "5ecfc871-5d82-43f1-9c54-59685e82318d",
"publisher": "LS Retail",
"name": "LS Central",
"version": "15.0.0.0"
}
]
Once done, download symbols again and you should see the app in your alpackages folder.