Distrubute iOS App On AirWatch - Same or alias sToken already exists in a peer Organizational Group

I want to distribute my iOS app in mdm with airwatch. But I want to distribute iOS app without appear on AppStore. Therefore I looked for and learned that I must use Apple Business Manager. I made all the preparations.

This preparations are:

1. To register Apple Business Account and get organization id
2. To submit app on AppStore with this options: "Available for private distribution to specific organizations on Apple Business Manager or Apple School Manager"

After that I registered a new account from airwatch and I went to the "APPS & BOOKS" page. After I clicked "Purchased" option, a pop up was appeared about to make "VPP Managed Distribution set up". So I went to "registration VPP Managed Distribution" page. This page required some information that is Descrption, sToken, Country etc. After that I downloaded sToken from Apple Business Manager Account. I tried to add this stoken to airwatch, but this error occured: "Same or alias sToken already exists in a peer Organizational Group."

Related screenshot is:

I don't understand why this error occurred. I haven't any experience on MDM solution.

I learned my colleague added our vpptoken to another mdm. I learned that a vpp token and a mdm would also be used. So I couldn't use it. I removed it from old test mdm. After I could use it.