Anonymous array not allowed as components

[L Dries <bertus.dries@planet.nl>]

I have an need for an array of Unbounded_Strings in which i define the 
elements.

I declared it as:

       Debug_Proc   : array (1 .. nr_Proc) of Unbounded_String :=
         (Debug_Proc(Lan),
          To_Unbounded_String("Only"),
          To_Unbounded_String("Empty_Buffer"),
          ...
          etc.

Then I got the message:

65:22 Anonymous array not allowed as components
This results i a position just before "array"

The value nr_Proc is defined in another package.
Debug_Proc(Lan) is an Unbounded String
I tried to replace nr_Proc by a value. The same result.
I tried to replave the value of the first Unbounded String by "--", 
again no result
I tried set it as an constant array, also no result.

What do I do wrong?
-- 
L. Dries