Access token not beeing refreshed automatically

i an not understand and will need more assistance.

in my up i am always using the DropboxTeamClient creating it with all the necessary parameters

like this.

var client = new DropboxTeamClient(request.AccessToken, request.RefreshToken, request.Expires, ClientId, ClientSecret);

now after that i am checking if the client is in the new space or the old one 

like this 

var account = await client.AsMember(request.AsMember).Users.GetCurrentAccountAsync();
var spaceclient = client.AsMember(request.AsMember).WithPathRoot(new PathRoot.Root(account.RootInfo.RootNamespaceId));

if (account.RootInfo.IsTeam)
{

metadata = await spaceclient.Files.ListFolderAsync(folderId);
}
else
{
metadata = await client.AsMember(request.AsMember).Files.ListFolderAsync(folderId)
}

now sometimes i need to call this 

client.Team.MembersListAsync().ConfigureAwait(false);

and befoe every call i  am calling the 

var client = new DropboxTeamClient(request.AccessToken, request.RefreshToken, request.Expires, ClientId, ClientSecret);

and I need it because that sometimes i am handing for the same client al the data content and all the user and groups as well 

and my issue is that after the token is expire i am getting the error that was in the first message .

400 error 

i am really need to get to the bottom  of this and understand is completely 

Thank you