[R] Question about 'logit' and 'mlogit' in Zelig

[Mathew, Abraham T]

I'm running a multinomial logit in R using the Zelig packages. According to str(trade962a), my dependent variable is a factor with three levels. When I run the multinomial logit I get an error message. However, when I run 'model=logit' it works fine. any ideas on whats wrong?

## MULTINOMIAL LOGIT
anes96two <- zelig(trade962a ~ age962 + education962 + personal962 + economy962 + partisan962 + employment962 + union962 + home962 + market962 + race962 + income962, model="logit", data=data96)
summary(anes96two)

#Error in attr(tt, "depFactors")$depFactorVar :
#  $ operator is invalid for atomic vectors


## LOGIT
Call:
zelig(formula = trade962a ~ age962 + education962 + personal962 + 
    economy962 + partisan962 + employment962 + union962 + home962 + 
    market962 + race962 + income962, model = "logit", data = data96)

Deviance Residuals: 
   Min      1Q  Median      3Q     Max  
-2.021  -1.179   0.764   1.032   1.648  

Coefficients:
               Estimate Std. Error z value Pr(>|z|)    
(Intercept)   -0.697675   0.600991  -1.161   0.2457    
age962         0.003235   0.004126   0.784   0.4330    
education962  -0.065198   0.038002  -1.716   0.0862 .  
personal962    0.006827   0.072421   0.094   0.9249    
economy962    -0.200535   0.084554  -2.372   0.0177 *  
partisan962    0.092361   0.079005   1.169   0.2424    
employment962 -0.009346   0.044106  -0.212   0.8322    
union962      -0.016293   0.149887  -0.109   0.9134    
home962       -0.150221   0.133685  -1.124   0.2611    
market962      0.292320   0.128636   2.272   0.0231 *  
race962        0.205828   0.094890   2.169   0.0301 *  
income962      0.263363   0.048275   5.455 4.89e-08 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

(Dispersion parameter for binomial family taken to be 1)

    Null deviance: 1841.2  on 1348  degrees of freedom
Residual deviance: 1746.3  on 1337  degrees of freedom
  (365 observations deleted due to missingness)
AIC: 1770.3

Number of Fisher Scoring iterations: 4




Thanks
Abraham