Below is the schedule that I am dealing with. The problem is that I cannot
find a rate that does not return a #NUM!. I've tried both negative and
positive return values and have not found one yet that returns something
other than #NUM!

3/27/2006 ($3,993.08)
4/1/2006 $871.42
5/1/2006 $871.52
5/3/2006 ($4,864.40)
5/3/2006 ($4,864.40)
6/1/2006 $870.51
6/2/2006 ($4,864.40)
7/1/2006 $870.04
7/5/2006 ($4,864.40)
8/1/2006 $869.06
8/3/2006 ($4,864.40)
9/1/2006 $868.53
9/6/2006 ($4,864.40)
10/1/2006 $868.53
10/4/2006 ($4,924.67)
11/1/2006 $867.95
11/6/2006 ($4,966.81)
12/1/2006 $866.79
12/4/2006 ($4,966.81)
1/1/2007 $866.19
1/8/2007 ($4,966.81)
2/1/2007 $866.19
2/5/2007 ($4,966.81)
3/1/2007 $910.86
3/5/2007 ($4,864.40)
4/1/2007 $910.20
4/5/2007 ($4,864.40)
5/1/2007 $909.34
5/3/2007 ($4,864.40)
6/1/2007 $908.50
6/4/2007 ($4,864.40)
7/1/2007 $908.02
7/5/2007 ($4,864.40)
8/1/2007 $907.87
8/3/2007 ($4,864.40)
9/1/2007 $906.91
9/4/2007 ($4,864.40)
10/1/2007 $905.77
10/3/2007 ($4,924.67)
11/1/2007 $905.17
11/5/2007 ($4,966.81)
12/1/2007 $904.60
12/6/2007 ($4,966.81)
1/1/2008 $904.60
1/7/2008 ($4,966.81)
2/1/2008 $904.79
2/6/2008 ($4,966.81)
3/1/2008 $942.92
3/6/2008 ($4,864.40)
4/1/2008 $941.97
4/3/2008 ($4,864.40)
5/1/2008 $940.92
5/5/2008 ($4,864.40)
6/1/2008 $940.48
6/2/2008 ($4,864.40)
7/1/2008 $941.24
7/2/2008 ($4,864.40)
8/1/2008 $941.24
8/4/2008 ($4,864.40)
9/1/2008 $940.68
9/5/2008 ($4,864.40)
10/1/2008 $942.05
10/6/2008 ($4,924.67)
11/1/2008 $944.31
11/3/2008 ($4,966.81)
12/1/2008 $945.74
12/3/2008 ($4,966.81)
12/28/2008 $92,520.92