>>I am trying to incorporate into my project a masked input plug-in (URL: http://digitalbush.com/projects/masked-input-plugin/)
>>
>>When I add this .js
>>

>><script src="Scripts/jquery-1.7.1.js" type="text/javascript"></script>
>><script src="Scripts/jquery.maskedinput-1.2.2.min.js" type="text/javascript"></script>
>>

>>to a separate .aspx file in my project, the mask() function works very well.
>>
>>But when I add it to a page that uses Master page, I get error:
>>

>>0x800a01b6 - Microsoft JScript runtime error: Object doesn't support property or method 'mask'
>>

>>
>>The test code is identical in separate test page and the page that uses master page:
>>
>>

>> <script type="text/javascript">
>>        $(document).ready(function () {
>>             $("#txtPhoneNumber").mask("(999) 9999-9999");
>>        })
>>    </script>
>>

>>
>>The error (above) happens on the line .mask() above.
>>
>>How would you recommend to debug this situation? TIA
>
>Do you have both scripts included into the master page ? (jQuery and plug-in)?

Yes, I have both scripts in the master page. And I also tried to add these scripts on a page where I use them. But to no avail.