Maybe an array bug in Unity 3

Hi i dont know why but in unity 3 (but not in 2.6) if i have this:

accountList = new Array( new Array("Name","Password"));

and i use for exemple:

//match the passwords
if (accountList[0][1] == _pass)
{
     ......
}

_pass is a variable that contain the password (a string)

i got internal complier error (BCE0055) at the accountList[0][1] , why?

Are you sure you want to use jagged arrays [ ][ ] ? and not the standard ones [,] ?