[R] Error when running Conditional Logit Model

[Hien Nguyen]

Dear R-helpers,

I am very new to R and trying to run the conditional logit model using 
"clogit " command.
I have more than 4000 observations in my dataset and try to predict the 
dependent variable from 14 independent variables. My command is as follows

clmtest1 <- 
clogit(Pin~Income+Bus+Pop+Urbpro+Health+Student+Grad+NE+NW+NCC+SCC+CH+SE+MRD+strata(IDD),data=clmdata)

However, it produces the following errors:

Error in fitter(X, Y, strats, offset, init, control, weights = weights,  :
  NA/NaN/Inf in foreign function call (arg 6)
In addition: Warning messages:
1: In Surv(rep(1, 4096L), Pinmig) : Invalid status value, converted to NA
2: In fitter(X, Y, strats, offset, init, control, weights = weights,  :
  Ran out of iterations and did not converge

I search the error message from R forums but it does not say anything 
for Conditional Logit Model.

Please check for me what it says and what should I do to solve it.

Thanks a lot for your help

Hien Nguyen