[R] Help on warning message from Neg. Binomial error during glm

I am using glm.nb, a ~b*c ( b is categorical and c is continuous). when I run this model I get the warning message: Warning messages: 1: In theta.ml(Y, mu, sum(w), w, limit = control$maxit, trace = control$trace : iteration limit reached 2: In theta.ml(Y, mu, sum(w), w, limit = control$maxit,

[R] Help on warning message from Neg. Binomial error during glm

I am using glm.nb, a ~b*c ( b is categorical and c is continuous). when I run this model I get the warning message: Warning messages: 1: In theta.ml(Y, mu, sum(w), w, limit = control$maxit, trace = control$trace : iteration limit reached 2: In theta.ml(Y, mu, sum(w), w, limit = control$maxit,