The macro that Xaices provided is the same one I use and it works fine. It could be issues with your connection because after you induce shadow step if you don't input a second ability within a certain amount of time the ability will fail.
I use it constantly and it works fine for me.
A tip: In case you didn't, write the macro
exactly as it is written above including the quotation marks, the capitalization, the spaces, everything. It is case sensitive and it needs the quotations and the appropriate spell level if it has one. Also, the number of the spell is in Roman Numerals, so "Harrow I" is with the letter I, not the number 1.
Remember, the second macro is missing a quotation mark in front of Shadow Step. it should be:
Code:
/cast "Shadow Step"
/em steps into the shadows.
/cast "Harrow I"