jQuery : Error: $(document).ready is not a function

This error is because another framework is in conflict with jQuery.
Use jQuery(document).ready(function() instead of $(document).ready(function() along with jQuery.noConflict();

 
For example:
Use:
<script>
jQuery.noConflict();
jQuery(document).ready(function(){
});
</script>

instead of:

<script>
$(document).ready(function(){
});
</script>