Have you set the trigger correctly to the channel with your signal, polarity and level? Do you undersand the difference between normal and auto trigger? Why don't you post a screendump. Are you ABSOLUTELY SURE that you have a signal on your cable? Have you tried with another oscilloscope? Are you sure that your SMA connector is good?
I have recently obtained a DRS4 Evaluation Board (V5), but I am unable to register signals when using the DRS Oscilloscope application. There seems to be some difference in noise when I have an input connected to a signal or not, but I am unable to view a simple, 0.2V amplitude square wave or other small signals. The only way I have been able to view a waveform is when connecting the reference clock to all channels. When running 'info' in the DRS Command Line Interface I am shown correct information. I was wondering if there is any way for me to test the functionality of the board (specifially ability to read signals on Ch 1-4) to ensure that it is indeed working as expected?