[Eeglablist] How to do TF analysis with eeglab

[wrpjoy]

Hi, all
I want to do time-frequency analysis with eeglab. My data is 3-minute-long steady state visual evoked potential. I have trouble with doing time-frequency anaylsis with eeglab. The message is "Epochs must be extracted before running the function". Only one epoch for my data. The time-frequency analysis can not be used for one- epoch  data? How can I do?
Thanks.

Wang R.P