Check if the HJJ_HUD.DLL gauge is declared in your DLL.XML file, the entry should be something like this, note your file path might be different depending on where you put the HJJ_HUD.DLL gauge:
Code:
<Launch.Addon>
<Name>HJJ_HUD</Name>
<Disabled>False</Disabled>
<ManualLoad>False</ManualLoad>
<Path>Addon Modules\HJJ_HUD.dll</Path>
<DllStartName>module_init</DllStartName>
<DllStopName>module_deinit</DllStopName>
</Launch.Addon>
EDIT: This is only valid for FSX, FSX-SE and 32 bit P3D versions. The 32 bit gauge does not work in P3Dv4.