Move-SpSite Operation is not valid error

I am trying to move a Site Collection to a new Content DB.

I ran "Move-SPSite http://portal/sites/sitecollectionName -Destination Database "new database name"

and it returned this error:

Move-SpSite: Operation is not valid due to the current state of the object. At Line:1 char:12 + move-spsite <<<<http://portal/sites/sitecollectionname -destinationdatabase "new database name" + CategoryInfo : InvalidData: <Microsoft.Share...PCmdletMoveSite: SpCmdletMoveSite> [Move-SPSite], InvalidOperationException + FullyQualifiedErrorId : Microsoft.Sharepoint.Powershell.SPCmdletMoveSite

I've tried researching this, and the answers I've found say to run the Upgrade_SpContentDatabase command.  I ran this command but it says that my database does not need to be upgraded.

I've tried this on more than 1 site collection and content db , and still get the same error.

Any suggestions?

thanks!