Mine does the same, try changing the chart to XY (Scatter) and take the ticks out of Automatic then change back to the chart you want, it seems to free up some of the values for you, I'm not sure if it is the ones you need though, you'll have to try it.
Tried that. It gets me to do some adjustments, but it will not pick up the date which is what I want in the X axis. Even checked for the "From Source" bit, still it will not pick up the date correctly. In fact with all the automatics removed in the scatter chart, I get a date which bears no relationship to what I want giving a start date of 31/12/1899 to 18/01/1900. It is a we bit before my time!!
I went through the OOo Help Forum, and despite some conflicting answers and some attempts at help, there appears to be nothing that can sensibly be done to alleviate the problem. I will carry on as I have been and not bother with any scaling. It is something to do with dates being text and not numerical!!