Hi - any Vegas experts out there?

After buying Pro8 last week I am trying out the Multicam facility. Have followed the manual :

- Chosen Quantise to frames
- Chosen Ignore Event Grouping
- Loaded the two clips in the timeline.

Then I have the problem. It says to choose Multicamera from the tools menu and choose either Layout Tracks Using Media Timecode/Layout Tracks Using Date/Time Stamp from the Submenu..

But these are both greyed out.

Anyone tell me what I am doing wrong please?

Thanks

Colin