Random in imacros

This code two years ago worked, but now shows error. I can not deal with it.

VERSION BUILD=1005 RECORDER=CR
SET !VAR1 EVAL("var letters = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','w','x','y','z']; var string = ''; for(var i = 0; i < 6; i++){string += letters[parseInt(Math.random() * 25)]}; string")
SET !VAR2 EVAL("var letters = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','w','x','y','z']; var string = ''; for(var i = 0; i < 6; i++){string += letters[parseInt(Math.random() * 25)]}; string")
SET !VAR3 EVAL("var letters = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','w','x','y','z']; var string = ''; for(var i = 0; i < 6; i++){string += letters[parseInt(Math.random() * 25)]}; string")
SET !VAR4 EVAL("var letters = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','w','x','y','z']; var string = ''; for(var i = 0; i < 6; i++){string += letters[parseInt(Math.random() * 25)]}; string")
SET !VAR6 EVAL("var letters = ['0','1','2','3','4','5','6','7','8','9']; var string = ''; for(var i = 0; i < 6; i++){string += letters[parseInt(Math.random() * 10)]}; string")
SET !VAR7 EVAL("var letters = ['0','1','2','3','4','5','6','7','8','9']; var string = ''; for(var i = 0; i < 2; i++){string += letters[parseInt(Math.random() * 10)]}; string")
SET !VAR8 EVAL("var letters = ['0','1','2','3','4','5','6','7','8','9']; var string = ''; for(var i = 0; i < 2; i++){string += letters[parseInt(Math.random() * 10)]}; string")
SET !VAR9 EVAL("var letters = ['0','1','2','3','4','5','6','7','8','9']; var string = ''; for(var i = 0; i < 9; i++){string += letters[parseInt(Math.random() * 10)]}; string")
SET !VAR5 EVAL("var letters = ['0','1','2','3','4','5','6','7','8','9']; var string = ''; for(var i = 0; i < 10; i++){string += letters[parseInt(Math.random() * 10)]}; string")

Error: BadParameter: Unsupported variable !VAR4, line: 5