# FeynCalc example — muon decay — integration issue

I'm just starting out using Mathematica and I'm trying to work through one of the examples given for FeynCalc, specifically the muon decay: https://github.com/FeynCalc/feyncalc/blob/master/FeynCalc/Examples/EW/Tree/Mu-ElAnelNmu.m

It seems to be working fine up until line 117,

diffDecayRate =
prefac d3q1/En[q1] d3q2/En[q2] d3k/En[k] delta4[q - q1 - q2] ampSquared[1]


The output for this is

(16 d3k d3q1 d3q2 Subscript[G, F]^2 delta4[q - Subscript[q, 1] -
Subscript[q, 2]] tr[-(OverBar[k] "\[CenterDot]" OverBar[Subscript[q, 1]])]
tr[-(OverBar[p] "\[CenterDot]" OverBar[Subscript[q, 2]])])) /
(En[k]*En[Subscript[q, 1]] En[Subscript[q, 2]])


that is:

which clearly isn't correct, and from there the integral cannot be evaluated. Has anyone else come across this, and is it immediately obvious what I might be doing wrong?