Judging from the large success stories, I'll presume no one is yet using ColorBase on a Mac along with a 4900. However, someone else may come along with a similar setup so I thought I would provide an update. I chatted with Epson UK late last week and was informed that the issue was something their business unit needed to discuss, they needed to run some tests and would get back with me. My hope is they ran a similar setup, the problem repeated itself and they are working on a fix. In the meantime, I printed a test chart from windows, read it, generated a calibration file and imported it on the mac side. Unfortunately, ColorBase 2.50 thought the file used PB ink and did not retrieve the paper type or resolution from the file. I also tried moving various definition files from the 2.50 package to the 2.40 package but could never get 2.40 to recognize the 4900 driver.