Built-in views such as the variable devicetype report are stored in the table tsysDBobjects in the Lansweeper database. The highlighted text needs to be modified to an actual asset type, as the view uses a variable, which won't work in the report builder.
SELECT tblAssets.AssetID, tsysAssetTypes.AssetTypeIcon10 AS Icon, tblAssets.AssetName, tsysAssetTypes.AssetTypename AS Type, tblAssetCustom.State AS Thestate, tblAssets.Domain, tblAssets.IPAddress AS [IP Address],
tblAssets.Description, tblAssetCustom.Manufacturer, tblAssetCustom.Model, tblAssetCustom.Location, tsysIPLocations.IPLocation, tblAssets.Firstseen, tblAssets.Lastseen, case when (tblassets.assettype = -1 and
COALESCE (tblassets.OSCODE, '') = '') then 'red' else 'black' end as foregroundcolor FROM tblAssetCustom
INNER JOIN tblAssets ON tblAssetCustom.AssetID = tblAssets.AssetID
LEFT OUTER JOIN tsysIPLocations ON tblAssets.LocationID = tsysIPLocations.LocationID
INNER JOIN tsysAssetTypes ON tblAssets.Assettype = tsysAssetTypes.AssetType
WHERE (tblAssets.Assettype = @devicetype) and (tblAssetCustom.State = 1)
ORDER BY tblAssets.AssetName