If you're referring to the text creation tool in Vegas, make sure to drag the box titled "Default Text" (as this is one of the transparent background versions) to the timeline and put it on a track on top of your video clip.
Also be sure to put the text on a separate track above the video rather than on the same track. If it's on it's own track it gets composited with the video. If you put it on the same track then it replaces the video.
Thanks for your advise but that is exactly my problem. If I put the default text over the video clip the screen become black when previewed eventhough the default text showed on the timeline is checkered as being transaparent.
Right click in the gray area below the video and audio track. Create a new video track. It should appear on top. Now, go to the top video track (which is the one you just created) and down below, click on the media generator tab and select "default text" with the checkered background. Drag this to the top track. On the other video track place your footage there and the text will be overtop of it. (Make sure you do not have the solo button checked on the track or it will show up exactly how you said, with black background as that track is the only one being played).
If I put the default text box on the 3rd timeline track (1 being video clip and 2nd being audio), I don't even get see the text.
That's normal behaviour for Vegas.
Do you see the video in the preview window before adding any text at all?
If the answer is no, make sure that the "Split Screen View" is set to "FX Bypassed" and not set to "Clipboard".
Another possibility is that you have the text track in "solo" mode.