Your Twitter metrics take some time to synchronize. We'll do that in the background, but when you first install your Twitter account, a lot of data will be missing.
If you've just installed your Twitter account, check back the next day and it will be completed. We'll start building the reports from scratch, since you add your Twitter account. There are no past back data we have access to.
If your Twitter account has been added several days ago but the report is still empty, please, let us know!