I too am experiencing this problem. My clients are running Win 7 Pro x64, with Adobe Reader 11.0.03 installed. It's my understanding that 11.0.05 will only upgrade 11.0.04. I've published the 11.0.04 msp, and all of my client computers have reported "Not Applicable." For the fun of it, I've also tried publishing the 11.0.05 msp as well. I get the same result. I have no supersedes, or rules/requirements defined. I basically just created the update, added the msp, input the title and other info, and published. If required, I will be happy to attach logs or whatever. Thanks!
edit : more info... I've tried this process with both the MUI and regular MSP
edit : more info... I've tried this process with both the MUI and regular MSP