Mismatch of results from Micromega for the same benchmark

Dear Experts,

I was trying to write a model file for mUED using FeynRules (I took the publicly available mUED file and just changed the dark-sector particles by adding a ~ prefix). I generated both UFO and CalcHEP model files. Then I tried to get the relic density using both Micromega and Maddm, keeping the parameters the same in both. But the results I get are different.

With Micromega, the results are:

Xf=41.0 Omega=1.55e-07

whereas for Maddm the results are:

 ****** Relic Density
OMEGA IS 0.044326
INFO: Relic Density = 4.43e-02 UNDERABUNDANT
INFO: x_f = 2.30e+01

For verification, I took the Lanhep model file of mued, where they have considered up to kk level 2, but in the FeynRule model file, they have considered up to kk level 1, so I changed the kk level in Lanhep to up to 1 (only for fermions)to make a comparison on the same footing. And got the answer like this:

Xf=2.84e+01 Omega=8.92e-02.

What might be the reason for this? What am I doing wrong here? Why is the freeze-out so different, while all the parameters are the same in both?

Any help regarding this would be much appreciated.

With regards
Debabrata Sahoo