MonoRail Select Using Enum - castle-monorail

Question

I've been following this guide and coming up with my own concoction in order to use MonoRail's FormHelper.Select that is generated from an enum. So here's the Brail syntax:
${FormHelper.Select("user.Role", ${LS.EnumToPairs(Roles)}, {"value":"First", "text":"Second"})}
"LS" is just my own helper, which I've defined as follows:
public IEnumerable<Pair<int, string>> EnumToPairs(Type e)
{
IList<Pair<int, string>> pairs = new List<Pair<int, string>>();
foreach (int val in Enum.GetValues(e))
pairs.Add(new Pair<int, string>(val, Enum.GetName(e, val)));
return pairs;
}
Yet from this, despite being the correct syntax, I get the following error:
Node '$({ return Castle.MonoRail.Views.Brail.ExpandDuckTypedExpressions_WorkaroundForDuplicateVirtualMethods.Invoke(self.GetParameter('LS'), 'EnumToPairs', (self.GetParameter('Roles'),)) })' has not been correctly
The source error doesn't help much unfortunately:
Line 15: output FormHelper.TextField("user.Role", {"class":"text-input full-width"})
Line 16: output """
Line 17: """
Line 18: output FormHelper.Select("user.Role", ${LS.EnumToPairs(Roles)}, {"value":"First", "text":"Second"})
Line 19: output """
Any ideas what I'm doing wrong here?
EDIT
Based on the answer given below, the solution was finally this:
${FormHelper.Select("user.Role", LS.EnumToPairs(Roles), {"value":"First","text":"Second"})}
Where Roles was PropertyBag["Roles"] = typeof(Role);

Answer 1

Try this:
${FormHelper.Select("user.Role", LS.EnumToPairs(typeof(Roles)), {"value":"First", "text":"Second"})}