Problem in sorting when some cell is empty using AW2.5

Hi all,i am having grid with some columns such as Emono,confirmdate,amount,Last name.Each columns would have some empty values in some of the rows. when i sorting this columns are not sorted well.Example
Emono confirmdate amount Last name
1001 1021 john
1002 04/11/2008 michel
1003 04/18/2008
1004 04/10/2008 1001 phelps
1005 1007 utsav

when i sort the confirmdate it displayed like
Emono confirmdate amount Last name
1001 1021 john
1004 04/10/2008 1001 phelps
1002 04/11/2008 michel
1003 04/18/2008
1005 1007 utsav

when i sort the amount it displayed like
Emono confirmdate amount Last name
1004 04/10/2008 1001 phelps
1001 1021 john
1002 04/11/2008 michel
1003 04/18/2008
1005 1007 utsav

so i need help how i can sort this columns. please help me Alex to come out this problem.

What i implies here is when i have column which contains some empty cell values. That column not sorting properly, so please help me anyone to out this problem.

http://www.activewidgets.com/javascript.forum.12384.5/formats-applied-to-empty-cells.html
Use dataToText OR dataToValue
http://www.activewidgets.com/aw.system.format/datatotext.html
http://www.activewidgets.com/aw.system.format/datatovalue.html