Unable to connect: incorrect log on parameters - In CMC / CR report

I have a CR report that connects to an AS400 and an Excel file. The Excel file is on a Network Drive, and I've made sure that the drive is mapped on my server that the Crystal Reports Server is on. I can sucessfully run this report on this same server in CR XI. However, when I try to Preview or Run Now from the CMC, it says "Unable to connect: Incorrect log on parameters".

I do not have a password on the Excel file, but this is where the problem seems to be. Any ideas?