Hi everybody. I'm trying to use margins command to estimate marginal effects for an interaction term after using nbreg command. This is the code I'm using:
Code:
  
nbreg Homicidio_total i.tratamiento##i.semana2 i.hora i.dia_semana, vce(cluster hora)
margins i.tratamiento##i.semana2, atmeans
My problem is that, as you can see below, the marginal effects for my different interactions of tratamiento#semana2 (semana2 has multiple values) are "(not estimable)". I believe this is related to the fixed effects included in my equation because when I delete i.hora and i.dia_semana from the code above, my problem disappears.

Does anybody know how can I estimate the marginal effects for my interactions without eliminating the fixed effects from my equation?
Code:
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                    |            Delta-method
                    |     Margin   Std. Err.      z    P>|z|     [95% Conf. Interval]
--------------------+----------------------------------------------------------------
        tratamiento |
                 0  |          .  (not estimable)
                 1  |          .  (not estimable)
                    |
            semana2 |
                 0  |   .0997079   .0268534     3.71   0.000     .0470762    .1523397
                 5  |   .1117857   .0202377     5.52   0.000     .0721206    .1514509
                 6  |    .146213   .0264997     5.52   0.000     .0942747    .1981514
                 7  |   .1414546   .0303556     4.66   0.000     .0819587    .2009506
                 8  |   .1614928   .0302981     5.33   0.000     .1021096     .220876
                 9  |   .1348336   .0268717     5.02   0.000      .082166    .1875012
                10  |   .1401169   .0263954     5.31   0.000     .0883829     .191851
                11  |   .1214307   .0261194     4.65   0.000     .0702376    .1726238
                12  |   .1625234   .0291322     5.58   0.000     .1054253    .2196216
                13  |   .1336381   .0308761     4.33   0.000     .0731221     .194154
                14  |   .1582381   .0394089     4.02   0.000     .0809981     .235478
                15  |   .1710773   .0392099     4.36   0.000     .0942274    .2479272
                16  |   .1180855   .0262798     4.49   0.000     .0665781    .1695929
                17  |   .1406704     .02768     5.08   0.000     .0864186    .1949223
                18  |   .1203476   .0177187     6.79   0.000     .0856195    .1550757
                19  |   .1304048   .0312392     4.17   0.000      .069177    .1916325
                20  |   .1174044   .0193162     6.08   0.000     .0795454    .1552635
                21  |   .1065888   .0224447     4.75   0.000      .062598    .1505795
                22  |   .0837027   .0197534     4.24   0.000     .0449867    .1224187
                23  |   .0823713   .0216225     3.81   0.000      .039992    .1247505
                24  |   .1333817   .0421092     3.17   0.002     .0508491    .2159142
                    |
tratamiento#semana2 |
              0  0  |          .  (not estimable)
              0  5  |          .  (not estimable)
              0  6  |          .  (not estimable)
              0  7  |          .  (not estimable)
              0  8  |          .  (not estimable)
              0  9  |          .  (not estimable)
              0 10  |          .  (not estimable)
              0 11  |          .  (not estimable)
              0 12  |          .  (not estimable)
              0 13  |          .  (not estimable)
              0 14  |          .  (not estimable)
              0 15  |          .  (not estimable)
              0 16  |          .  (not estimable)
              0 17  |          .  (not estimable)
              0 18  |          .  (not estimable)
              0 19  |          .  (not estimable)
              0 20  |          .  (not estimable)
              0 21  |          .  (not estimable)
              0 22  |          .  (not estimable)
              0 23  |          .  (not estimable)
              0 24  |          .  (not estimable)
              1  0  |          .  (not estimable)
              1  5  |          .  (not estimable)
              1  6  |          .  (not estimable)
              1  7  |          .  (not estimable)
              1  8  |          .  (not estimable)
              1  9  |          .  (not estimable)
              1 10  |          .  (not estimable)
              1 11  |          .  (not estimable)
              1 12  |          .  (not estimable)
              1 13  |          .  (not estimable)
              1 14  |          .  (not estimable)
              1 15  |          .  (not estimable)
              1 16  |          .  (not estimable)
              1 17  |          .  (not estimable)
              1 18  |          .  (not estimable)
              1 19  |          .  (not estimable)
              1 20  |          .  (not estimable)
              1 21  |          .  (not estimable)
              1 22  |          .  (not estimable)
              1 23  |          .  (not estimable)
              1 24  |          .  (not estimable)
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