Chart in Excel 2007

Guys,

I'm having a problem in Excel 2007 which is as follows:

I have a spreadsheet with some data from monthly development and on top of these figures I put up two charts demonstrating this trend. The graphics displayed in the spreadsheet have the same database, but show divergent results. The second line of the second graph does not represent the reality of the chart.

Someone has seen this problem?

Thank you,

fareas