For exception... java.lang.NoClassDefFoundError: jxl/format/CellFormat

Hi all..

I am doing Download to Excel Functionality. For that i added jxl.jar file into my exterbal jar file. But in runtime i am getting this exception..

java.lang.NoClassDefFoundError: jxl/format/CellFormat

for this what should i will do? anybody explain to me..

it's very urgent..

with regards,

Gobinath.R