My Master Collection CS5 Serial # is invalid.

if you have a serial number for master collection cs5, you must install dw from the master collection installation file(s).

Downloads available:

• Suites and Programs:  CC 2014 | CC | CS6 | CS5.5 | CS5 | CS4 | CS3
• Acrobat:  XI, X | 9,8 | 9 standard
• Premiere Elements:  12 | 11, 10 | 9, 8, 7
• Photoshop Elements:  12 | 11, 10 | 9,8,7
• Lightroom:  5.5 (win), 5.5 (mac) | 5.4 (win), 5.4 (mac) | 5 | 4 | 3
• Captivate:  8 | 7 | 6 | 5
• Contribute:  CS5 | CS4, CS3

Download and installation help for Adobe links

Download and installation help for Prodesigntools links are listed on most linked pages.  They are critical; especially steps 1, 2 and 3.  If you click a link that does not have those steps listed, open a second window using the Lightroom 3 link to see those 'Important Instructions'.