Just thought I'd share some info I discovered.
Recently found a bug in MDT version 8443 (can also be in earlier versions for all I know), integrated with SCCM.
Noticed that the variable SMSDP would not set.
The variable value of SMSDP turned blank after replacing older scriptfiles with the newest.
To fix this you'll need to:
1. Edit the ZTIGather.wsf file with notepad or whatever
2. CTRL + F / search for SMSDP
3. This should bring you to line 1096 where you'll see:
arrSMSDP = Split(oEnvironment.Item("_SMSTS" & oEnvironment.Item("_SMSTSBootImageID")),",")
The line is supposed to be:
arrSMSDP = Split(oEnvironment.Item("_SMSTSHTTP" & oEnvironment.Item("_SMSTSBootImageID")),",")
4. Update your MDT Script package
Setting the correct variable to "_SMSTSHTTP" SMSDP was once again populated correctly.
Hope this will be helpful.