Problem with NIntegrate over a user-defined region

Question

I define a region as follows:

In[259]:= \[ScriptCapitalR] = 
  Polygon[{{0, 0}, {Re[gam2], Im[gam2]}, {gam1 + Re[gam2], 
     Im[gam2]}, {gam1, 0}}] ;
Graphics[\[ScriptCapitalR]]

According to http://reference.wolfram.com/language/ref/NIntegrate.html, I should be able to integrate over this region simply as follows:

NIntegrate[x^2 *y^2, {x, y} \[Element] \[ScriptCapitalR]]

But I keep getting this error:

NIntegrate::vars: Integration range specification {x,y}\[Element]\[ScriptCapitalR] is not of the form {x, xmin, ..., xmax}. >>

Why is that?

Answer 1

Works for me:

gam1 = 2; gam2 = 1 - 2 I;
ℛ = Polygon[{{0, 0}, {Re[gam2], Im[gam2]}, {gam1 + Re[gam2], 
    Im[gam2]}, {gam1, 0}}];

NIntegrate[x^2*y^2, {x, y} ∈ ℛ]
(*
  18.3111
*)