javascript - Filtering combobox not working for common store combos -

i using extjs 2.3. have 3 comboboxes following stores.
here, combo2 , combo3 share same store.

following combo stores-

combo1 store:
vice president
manager
employee
student

combo2 , combo3 store:
assignments
meetings
salary

now requirement is, if 'student' selected combo1, 'salary' should filtered out combo2 , 3 (it should not display 'salary' option)

i doing following code on change listener of combo1-

listeners: {         change: function(combo, record, index) {            var combo1val = combo.value; // give selected value correctly           this.filtercombo(combo1val , combo2);           this.filtercombo(combo1val , combo3);         }  } 

and function body

filtercombo: function (combo1val , combo) {       if (combo1val  ==  'student') {          combo.store.filterby(function (record) {               return record.get('text') != 'salary';          });       }       else {          combo.store.clearfilter();       } } 

the problem here first time when select student combo1, 'salary' option disappears combo2. then, when expand combo3, displays salary option there, , again whwn click on combo2, again displays 'salary' option. somehow filter not working.

can tell doing wrong here.

you can try in combo2

listeners: {     expand: function(combo) {         combo.store.clearfilter();         if (combo1val  ==  'student') {             //filter         }     } }