[R] help with Gantt chart

[Zoppoli, Gabriele (NIH/NCI) [G]]

Hi,

I don't know to solve this error that is returned, even though I understand it:

library(plotrix)

Ymd.format<-"%Y/%m/%d"
 gantt.info<-list(labels=
  c("First task","Second task (1st part)","Third task (1st part)","Second task (2nd part)","Third task (2nd part)",
	"Fourt task","Fifth task","Sixth task"),
  starts=
  as.POSIXct(strptime(
  c("2010/01/01","2010/07/01","2010/10/01","2011/04/01","2011/07/01","2011/07/01","2012/01/01","2012/07/01"),
  format=Ymd.format)),
  ends=
  as.POSIXct(strptime(
  c("2010/06/30","2010/09/31","2011/03/31","2011/06/31","2011/12/31","2012/06/30","2012/06/30","2012/12/31"),
  format=Ymd.format)),
  priorities=c(1,2,3,4,5))
 vgridpos<-as.POSIXct(strptime(c("2010/01/01","2010/04/01","2010/07/01",
  "2010/10/01","2011/01/01","2011/04/01","2011/07/01","2011/10/01",
  "2012/01/01","2012/04/01","2012/07/01","2010/10/01"),format=Ymd.format))
 vgridlab<-
  c("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec")
 gantt.chart(gantt.info,main="My First AIRC Grant Gantt Chart",
  priority.legend=TRUE,vgridpos=vgridpos,vgridlab=vgridlab,hgrid=TRUE)

Error in if (any(x$starts > x$ends)) stop("Can't have a start date after an end date") : 
  missing value where TRUE/FALSE needed


Thanks 


Gabriele Zoppoli, MD
Ph.D. Fellow, Experimental and Clinical Oncology and Hematology, University of Genova, Genova, Italy
Guest Researcher, LMP, NCI, NIH, Bethesda MD

Work: 301-451-8575
Mobile: 301-204-5642
Email: zoppolig at mail.nih.gov