[O] label and ref in latex export

[Vikas Rawal]

The following has been taken from my org file.

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#+CAPTION: Average output, cost and net income per acre, by area, (2005-06 
prices)
#+LABEL: tab:avprofit
#+ATTR_LATEX: table * tabulary width=\textwidth align=l|RRRR
#+BEGIN_SRC R :results value raw :colnames yes :hline yes
  subset(a,Crop_group=="Paddy")->a
  a[,c(8:10)]*a[,6]/a[,7]->a[,c(8:10)]
  vtab1(a,8,10,1,wtd.mean)->a1
  round(as.numeric(as.character(a1[,2])))->a1[,2]
  round(as.numeric(as.character(a1[,3])))->a1[,3]
  round(as.numeric(as.character(a1[,4])))->a1[,4]
  names(a1)<-c("Area","output","Cost","Net income")
#+END_SRC

\ref{tab:avprofit} shows that the average levels of are highest in
Area 7.

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When I export it to latex/pdf, \ref{tab:avprofit} is just shown as ??.
What am I not doing correctly? 

Also, is it okay if the text where the table is referenced comes
before the table (and therefore its label) itself?

Vikas