Call javascript on Webusercontrol

Question

Hi:
        I am using javascript calendar .I have placed text box, Calendar image on WebUsercontrol.Now i pic and placed the webusercontrol on .aspx page.After debugging  i just click the calendar image, calendar(javascript) was opened.Now i selected the date , the date should be placed on the text box instead i have got the following javascript error.

Error:
 

'self.opener.document.txtDate' is null or not an object.

Can we call javascript on webusercontrol and use the webusercontrol on .aspx page.

Plz let me know the solution.Its very urgent