Script encoder is given out by Microsoft so encode scripting language.
Not many ppl known this for a few reasons.
First- It serves them not much to encrpyt the source code since it server side code.
Second- Its can be easily decoded using other tools.
Thrid- There won't be any enchancement to the current script encoder.
But nevertheless it is quite useful to encryt your scrpting code and make it just 1 level harder for other ppl to read.
So for your problem my fren...you should try running the command screnc from the folder where u'r screnc.exe is located.
Thus if u want to encrpyt the html file, then put u'r screnc.exe in that folder and run the dos command from the folder. Get wat I'm saying?