getting an element by its id - odd behavior

getting an element by its id - odd behavior

i have an id of a div which is dynamically created which is of the form 'aa,bb,cc,dd'

i also have a div which has an id of 'aa'

when i use the following code:

var startTdId = 'aa,bb,cc,dd';
$('#'+startTdId)...

the element that is returned has the id 'aa'

are the commas causing some mishap and the id is not being correctly parsed or something? ideally, i want to be returned the element with id of aa,bb,cc,dd not aa

how do i get around this??

thanks in advance.