The 'Database' with 'ID' = 'xxxxxxx' doesn't exist in the collection

I have a SSAS Tabular server with 30 database. I also have a scheduled process to backup all databases daily. When I run the process which is an SSIS package with script task using AMO, I get this error : > The 'Database' with 'ID' = 'nameofdatabase' doesn't exist in the > collection. The backup process is running under the service account credential and it successfully backs up 27 databases but fails for only 3 of them. I checked those databases and don't see anything special on them. I googled the error message and most of the issues are related to deploying or processing the database. I don't see any reason for failing the backup. What is the problem and how I can resolve this issue?