Drop down selections based on a previous selection

HI,

Is there a way to have multiple drop down selection lists which are filtered based on the users previous(drop down in another cell) selection.

Below is what the initial sheet looks like. The majority of the selections here have drop down menus:

I have added a link to the image here: http://s1080.photobucket.com/user/Sonic1506/media/Untitled2.jpg.html

Below shows another sheet where the selections of the drop down box lies:

I have added a link to the image here: http://s1080.photobucket.com/user/Sonic1506/media/untitled1.jpg.html

I would like to code the spreadsheet so that If the user selects "002 - Buyer/Sales" in the "Contact Type" drop down then only the following relevant buying selections from "Role of Person" will show in the drop down box, "001 - Crime Buyer", "002 - Fiction Buyer", etc..

I found another thread here with some code that I have tried to adapt however when I try to adapt it it doesn't work.

(the following is the code I have found: 

A possible approach would be the following:

Create a table like this (maybe on a sheet "System"):

IT	Marketing - Client Services	Corporate Finance	Executive Management
IT	UMA AE 1	Corporate Finance	Marketing Head
 	UMA AE 2	 	CEO
 	Affinity AE 1	Corporate Finance Head
 	Affinity AE 2	Underwriting Head
 	Corporate AE 1	 
 	Corporate AE 2	 
 	PR	 	 
 

Define a Name "Departments" for the first line and define for your A1 cell a validity check that allows a list. Assign =Departments to this list.

Next define a calculated Name "Subdepartments" with the following formula:

=OFFSET(System!$A$2;0;MATCH(Sheet1!$A$1;Departments;0)-1;COUNTA(OFFSET(System!$A$2;0;MATCH(Sheet1!$A$1;Departments;0)-1;100;1));1)

Assign =Subdepartments as a valid list for Sheet1!$A$2.

Explanation of the formula: MATCH searches in the header of the table for the position of the string that the user selected in the cell A1 and returns the number of the column (1-4). OFFSET creates a new range beginning with the first cell of the second row, shifts it to the right by the just found number minus 1 and modifies the length of the list according to to number of elements found in this column (COUNTA).

Can anyone help? Is it even possible to do this?

Many thanks!