Package Ignores Environment Variable For ConnectionString

We're attempting set the ConnectionString for our configuration database connection manager from an environment variable, but SSIS seems to ignore the environment variable value. Deployment process:


Create the Connection Manager

Create an Environment Variable type configuration with the Target Property: Package.Connections[acConfigDBManager].Properties[ConnectionString]

Build the package

Copy the package and the manifest from the project's inDeployment folder to a folder on the server

From the SSIS server's console, Import the package from the File System.

Run the package, after first inspecting the ConnectionString in the Connection Managers collection
In all cases, the ConnectionString variable for our configuration database is the value in the package at build time.

So far we've tried the following variations:


confirmed that the spelling and case of the environment variable is identical on the XP development computer and the Win2003 server.

restarted SQL Server and SSIS

rebooted the Win2003 server.

built the package with a blank ConnectionString value in the connection manager

re-imported the package, overwriting the old one

deleted the old package before reimporting

renamed the package and imported

run imports from SQL Management Studio from the server console

assign the connection string from an arbitrary system environment variable

assign the ServerName and use an expression to build ConnectionString
What now? Has anyone been able to set a Connection Manager property from an environment variable?