I experienced a similar proble. The cause appears to be the case givent to your select tag under its propert name, hence in your .jsp file
<html:select property="mySelect"> is O.K. whereas
<html:select property="MySelect"> is NOT. Presumably, the struts Form class uses introspection and BeanInfo and expects the getter to be
public String[] getMySelect() {
return mySelect;
}
a capitalised MySelect seems to throw this off kilter.
Good Luck,
Simon