If the simultaneous record and playback option is grayed out, there is nothing in Cakewalk itself that can make it an option for you. The card either does not support
full duplex or there is a problem with the driver. Here are some things you can try:

1.Download and install the latest driver for the card. If you are using the latest driver, try re-installing it.
2.Close Cakewalk and delete the CW9AUDX file from the Cakewalk directory. If you have a file named TTSAUDDX.INI or AUDMM.INI, delete that as well.
3.Disable any voice modems in your computer in Control Panel, Multimedia, Advanced, Audio Devices. Then restart your computer.
4.Start Cakewalk. Click OK when asked about Profiling Your Audio Hardware.

See if the option has become available to you now.