Why can't add 2 devices to the app?

[Ckkats]

I used to have 2 devices on the same app. One device died,, and now I want to add the new replacement and it won't add it. I can switch from to the other, but the app won't let  me add t the e new kne. What is wrong.wrong 

[JohnnyRow]

Is the replacement the same model, or a different one?

[Ckkats]

Different. One is a versa the other is a charge4

Sent from my iPad

[JohnnyRow]

Sorry, I wasn't clear.  I meant is the replacement the same model as the one it replaced.  Certain combinations are not allowed.

See Can I use more than one Fitbit device with the same account? 

Note that you can't connect multiple devices that use the Fitbit App Gallery to one account. For Fitbit Charge 3, Fitbit Charge 4, Fitbit Ionic, Fitbit Inspire series, and Fitbit Versa series, only connect one of these devices to your account at a time.

[Ckkats]

No one responded to my last question. Is there an app out there that can handle both my versa and my charge 4 as I like to use both. One on my ankle

and one one my wrist.