Integrate tool says dpatial references don't match when they do

LindsayRaabe_FPCWA

I have 2 polyline feature classes and I'm trying to use the Integrate tool to close gaps between lines where one road doesn't quite meet another. 

 

Both datasets are spatial reference 4283 (Geocentric Datum of Australia 1994), and I've even made the map the same spatial reference, but despite the tool running to completion, nothing changes and I get the below warning:

What am I missing here?

Tool inputs below for reference:

 

LindsayRaabe_FPCWA

Small breakthrough. I exported a small area of the 2 datasets and Projected it into a Projected spatial reference and tried the Integrate tool again. It still didn't do anything, until I added in a tolerance of 15 metres and sure enough, the 2nd dataset moved to colocate features with verticies of the 1st. Will try again on the larger datasets once I've projected them as well.