Trying to do a 3d contest, I encountered the same problem about IES file.
"Error: 4] invalid horizontal angles in IES file"
After some investigations I found the solution.
I was helped by this guidehttp://www.vuw.ac.nz/architecture-onlin ... ormat.html
In my IES file I have the last horizontal angle as 355.
In that IES guide there is wrotten
"The last angle determines the degree of lateral symmetry displayed by the intensity distribution. If it is 0 degrees, the distribution is axially symmetric. If it is 90 degrees, the distribution is symmetric in each quadrant. If it is 180 degrees, the distribution is symmetric about a vertical plane. If it is greater than 180 degrees and less than or equal to 360 degrees, the distribution exhibits no lateral symmetries. All other values are invalid."
So I've changed my last value to 360 instead of 355 and now luxrender is fine...no more error.
Do you think it's possible to give into the log a message that suggest to use 90, 180 or 360??