SQL Server PowerShell error Get-ChildItem - sql-server

Question

I try to get backup from SQL databases with this PowerShell code:
Set-Location "SQLSERVER:\SQL\computer\distance\Databases"
foreach ($database in (Get-ChildItem)) {
$dbName = $database.Name
Backup-SqlDatabase -Database $dbName -BackupFile "E:\bu\$dbName"
}
In a virtual server it works.
When I go to SQLSERVER:\SQL\computer\distance\Databases location and take ls
it show my databases and sucessfully takes backups.
But in another server in my workplace it gives this error:
Get-ChildItem : SQL Server PowerShell provider error: Failed to read child items.
[Failed to connect to server computer\instance. --> Login failed for user
'work\sql'.]
At line:1 char:23
+ ForEach($database in (Get-ChildItem))
+ ~~~~~~~~~~~~~
+ CategoryInfo : ReadError: (SQLSERVER:\SQL\...\instance\Databases:SqlPath) [Get-ChildItem], GenericProviderException
+ FullyQualifiedErrorId : CannotReadChildItems,Microsoft.PowerShell.Commands.GetChildItemCommand
and when in SQLSERVER:\SQL\computer\distance\Databases directory I do ls it gives this error:
ls : SQL Server PowerShell provider error: Failed to read child items. [Failed to
connect to server computer\instance. --> Login failed for user 'work\sql'.]
At line:1 char:1
+ ls
+ ~~
+ CategoryInfo : ReadError: (SQLSERVER:\SQL\...\instance\Databases:SqlPath) [Get-ChildItem], GenericProviderException
+ FullyQualifiedErrorId : CannotReadChildItems,Microsoft.PowerShell.Commands.GetChildItemCommand
computer\instance: I changed for this example.