using Encrypt model with the dashboard. can't get the archive file.

i have learn the vedio of WWDC2020.
i use the objectC method :beginAccessingModelCollectionWithIdentifier:completionHandler: to retrieve the archive file from  the dashboard . where i recrive the wrong message:

Code Block language
[coreml] MLModelCollection: namespace (87HGLU5YX9.DeploymentModelCollection) download failed. Error Domain=com.apple.trial Code=0 "Unknown error." UserInfo={NSLocalizedDescription=Unknown error.}

the second time i running the app, i got the wrong message:

Code Block language
[coreml] MLModelCollection: experimentId unexpectedly not returned

device: iphone7 ios14.0.1
xcode: Version 12.0.1 (12A7300) ios deployment target 14.0

can you help me? thanks.