Child text from Parent window

I use the following code to populate a child windows from a parent. However when one of the text fields on the parent window is blank the code stops and does not continue. Please help I know it is something simple but I am new to this.

function onload()
{
thisAppl.AppName.value = opener.document.thisForm.ApplName.value ;
thisAppl.AppMailAddress.value = opener.document.thisForm.ApplMailAddress.value ;
thisAppl.AppHomeCity.value = opener.document.thisForm.ApplMailCity.value;
thisAppl.AppGarageAddress.value = opener.document.thisForm.ApplGarageAddress.value;
thisAppl.AppGarageCity.value = opener.document.thisForm.ApplGarageCity.value;
thisAppl.AppHomePhone.value = opener.document.thisForm.ApplHomePhone.value;
thisAppl.AppWorkPhone.value = opener.document.thisForm.ApplWorkPhone.value;
thisAppl.AppWorkExt.value = opener.document.thisForm.ApplWorkExt.value;
thisAppl.AppEmail.value = opener.document.thisForm.ApplEmail.value;
thisAppl.EffectiveDate.value = opener.document.thisForm.ApplEffDate.value;
}

Thank you

Have you got this up online anywhere, so we can take a look? If an error is occuring, your browser should tell you.

No I do not. It is on a test machine. What should I look for in the browser?