I have the report that shows all the devices not on the current Windows 10 build, which works fine. However, when I run it some machines from previous years show up on it. 
How can I add to this report, criteria that only queries devices that have been seen in the last 30 days.
I added:
 < GetDate()- 30
But it did not change the results. 
Select Top (1000000) tsysOS.Image As icon,
  tblAssets.AssetID,
  tblAssets.AssetName,
  tsysOS.OSname As OS,
  tblAssets.OScode + '.' + tblAssets.BuildNumber As Build,
  tblAssets.Version As [OS Version],
  tblAssets.Domain,
  tblAssets.Username,
  tblAssets.Userdomain,
  tblAssets.IPAddress,
  tblAssets.Description,
  tblAssetCustom.Manufacturer,
  tblAssetCustom.Model,
  tblAssetCustom.Location,
  tsysIPLocations.IPLocation,
  tblAssets.Firstseen,
  tblAssets.Lastseen
From tblAssets
  Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
  Inner Join tsysOS On tblAssets.OScode = tsysOS.OScode
  Left Outer Join tsysIPLocations On tblAssets.LocationID =
    tsysIPLocations.LocationID
Where (tsysOS.OSname = 'Win 10' And tblAssets.Lastseen < GetDate() - 30 And
  tblAssetCustom.State = 1 And tblAssets.BuildNumber Is Not Null And
  Cast(Replace(Replace(Replace(tblAssets.OScode, '.', ''), 'S', ''), 'R',
  '') As bigint) Not In (Select Max(Cast(Replace(Replace(Replace(tsysOS.OScode,
        '.', ''), 'S', ''), 'R', '') As bigint)) As Expr1 From tsysOS
      Where tsysOS.Sortorder = 18)) Or
  (tsysOS.OSname = 'Win 10' And tblAssetCustom.State = 1 And
  tblAssets.BuildNumber Is Not Null And tblAssets.BuildNumber Not In (Select
        Max(tblAssets.BuildNumber) As Expr1 From tblAssets
      Where Cast(Replace(Replace(Replace(tblAssets.OScode, '.', ''), 'S', ''),
        'R', '') As bigint) In (Select
              Max(Cast(Replace(Replace(Replace(tsysOS.OScode, '.', ''), 'S',
              ''), 'R', '') As bigint)) As Expr1 From tsysOS
            Where tsysOS.Sortorder = 18)))
Order By tblAssets.AssetName