mlogit Error in solve.default(H, g[!fixed]) : Lapack routine dgesv: system is exactly singular: U[2,2] = 0

Question

I want to transform my data to a mlogit.data and I did this

a<- mlogit.data(Fit.Train.KNN, choice ="Vote", 
                shape = c("wide"),
  alt.levels = c( "Scioli","Macri",
                  "Massa", "Carrio", "Sanz ","Stolbizer", "Indecisos", "Voto en blanco"))

When I did this the data was cool, have chid and alt and in the choice put True when a man vote for a candidate and false for the other options.

But when I want to do the model of mlogit:

Model.mulnom<- mlogit("Vote " ~ "Gender" , shape = c("long"), id="id",
                        alt.levels = c( "Scioli","Macri",
                                        "Massa", "Carrio", 
                                        "Sanz ","Stolbizer", "Indecisos", 
                                        "Voto en blanco") ,
                        reflevel= "Scioli",choice = "Vote", data= a
                        ) 

I get the following error message. I thought that the code was right and I don't know where the problem is.

**Error in solve.default(H, g[!fixed]) : 

  Lapack routine dgesv: system is exactly singular: U[2,2] = 0**