SQL Server表与索引同义词

I have multiple databases on a single instance of SQL Server 2005. I've created a synonym on one database to access a table on another database and when writing my queries, I'd like to utilize a specific index, however, when evaluating the execution plan, it doesn't appear to use it. If I write the query to access the database explicitly, it works, but I can't seem to get it to work using a synonym. For example:I have multiple databases on a single instance