Hello, At the moment, R-tryEval (src/main/context.c) : SEXP R_tryEval(SEXP e, SEXP env, int *ErrorOccurred) would set ErrorOccurred to 1 and return NULL when an error occurs during the evaluation of e within env, so to know that an error occured, we can just look at the ErrorOccured value and not look at the returned value. Could this be expanded so that, when an error occurs, something more useful than NULL is returned, such as the call stack for example. Romain -- Romain Francois Professional R Enthusiast +33(0) 6 28 91 30 30 http://romainfrancois.blog.free.fr |- http://tr.im/xMdt : update on the ant package |- http://tr.im/xHLs : R capable version of ant `- http://tr.im/xHiZ : Tip: get java home from R with rJava