Stargazer does not show standard errors

Dear Community
I have a problem. I calculated many different models with OLS. Because of heteroskedasticity, I calculated robust standard errors. Because i have Panel data, I calculated a model with Country fixed effects (with least squares dummy variables). The problem is, that stargazer opens me a table without standard errors in parentheses. The table that i receive shows just the coefficiennts. Therefore, I cannot see whether the estimates are significant.
R was not able to compute the robust standard errors using the command below(NaN for every variable...)
I have over 20 dummy variables . Is it possible that the problem might arise because of this? In the model with time fixed effects (4 Dummy variables), everything worked.

rob.set1<-sqrt(diag(vcovHC(fixed.time1)))

(fixed.time1 is the name of my regression model)

Thank you for your help in advance!