Excel Chart does not have correct value

Giganews Newsgroups
Subject: Excel Chart does not have correct value
Posted by:  Two-Canucks
Date: Thu, 11 May 2006

I have a line charts using a Date column
and two Value columns.
For 24 cells, everything works OK. With
the 25th entry the line turns sharply down
and shows an incorrect value!! This happens
even when I leave the entry empty!! When
I continue filling in data as a test the chart is
again correct.

Monday, May 08, 2006    36780.63
Tuesday, May 09, 2006    36948.93
Thursday, May 11, 2006    36496.29

Last point on line shows: Thursday, May 11, 2006  $29842.71
instead of $36496.29

What could cause this?
Many thanks

Occasionally stumped