ASP.NET Which validationgroup caused validation fail

Question

There are 3 validation groups on the page

Group1 Group2 Group3

After calidating the groups

Page.Validate("Group1");
Page.Validate("Group2");
Page.Validate("Group3");

Page.IsValid is false

How to find out which group caused validation fail and wich passed ?

Answer 1

Check Page.IsValid after each call.

Answer 2

Why not checking right after calling validate?

Answer 3

Page.Validate("Group1");
if (!Page.IsValid)
    return "Group 1 did not validate";

Page.Validate("Group2");
if (!Page.IsValid)
    return "Group 2 did not validate";

Page.Validate("Group3");
if (!Page.IsValid)
    return "Group 3 did not validate";