Scatter Chart invents x-axis data??

Hello:

I am trying to create a simple scatter chart using daily data consisting of dates and then teh data consists of zeros and plus and minus 1's and 2's. When I plot the data using a line chart, I get the first two charts in the attached file. While this contains all the dates in the data, I wish to have only dots instead of lines emanating from the x-axis. When I try to make a scatter chart in the third chart, it includes dates that are not even in my data set. Any clue why?

Thanks
SB