Membership.ValidateUser always false

Hi,

I would like to check of a username and password is correct...

Dim returnValue As Boolean
returnValue = Membership.ValidateUser(Me.Username.Text.ToString,
Me.Password1.Text.ToString)

.... Before adding them as user ....

Membership.CreateUser(Me.Username.Text.ToString, Me.Password1.Text.ToString,
Me.Mail.Text.ToString)

.... But ir returns always "false"

Does anyone have a solution ... ?



Thanx