Hi Experts

i have 2 problems

1. while i m trying to checkout the user availability in reg. form

for that i found Ext.ux.plugins

i m using the following code. but in IE i m getting the error "exception thrown but not caught" i m using extjs 3.0 .
xtype: 'textfield',
fieldLabel: 'Username',
blankText: 'UsenName is required',
rvOptions: {url:'validate.php'}

2.Onselect an item from combo i need to show a list of items with radiobuttons

plz give me some examples