Either you are looking only on a specific software version, but the other computers have another version of the software installed, or the other computers are not in Active state. Most web console pages and built-in reports will only list assets in State Active. The following report could help you to filter on a specific software name and listing all versions which are present in your network.
Select Top 1000000 tblAssets.AssetID,
tblAssets.AssetName,
tsysAssetTypes.AssetTypeIcon10 As icon,
tblAssets.Lastseen,
tblSoftwareUni.softwareName,
tblSoftwareUni.SoftwarePublisher,
tblSoftware.softwareVersion
From tblAssets
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
Inner Join tblSoftware On tblAssets.AssetID = tblSoftware.AssetID
Inner Join tblSoftwareUni On tblSoftwareUni.SoftID = tblSoftware.softID
Where tblSoftwareUni.softwareName Like '%example software%' And
tblAssetCustom.State = 1