Find module that contains function

Get-Command isn't doing what I expected...

C:\Users\hxchba
> get-command | where { $_.Name -Like “dh” }

CommandType Name        ModuleName
———–             —-            ———-
Function            dh

Why is “ModuleName” blank? How can I work around this?
Thanks –

PSVersion                      4.0
WSManStackVersion              3.0
SerializationVersion           1.1.0.1
CLRVersion                     4.0.30319.18408
BuildVersion                   6.3.9600.16406
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0}
PSRemotingProtocolVersion      2.2