Error Restore database to secondary - Log Shipping

I am new as a DBA. I want to ask. I want to create new log shipping a database 17815 from server primary to server secondary. I create new log shipping with right-click on database 17815. when I click ok, but I get this error

System.Data.SqlClient.SqlError: The file 'M:\MSSQL10_50.MSSQLSERVER\MSSQL\DATA\PREUATPSSHSOH123CAB_Data.mdf' cannot be overwritten.  It is being used by database '13722'.

So what can I do? I was trying to restore manually with the restore command, and restore was successful. However, when I try to create new log shipping again, the error is the same.