QTP Object Required Error due to dynamic change in Web - automation

Question

When an action is performed, it will last for a while to get a message showing that this action is successful. Here I use a function to test if the message comes out:
For i = 0 To NumberOfiframe - 1
Set objPage = iframe(i).Object
Set objTag = objPage.GetElementsByTagName("span")
intTotalLink = objTag.Length - 1
For intCtr = 0 to intTotalLink
If objTag(intCtr) = null Then
Exit Function
End If
strContent = objTag(intCtr).InnerText
endPosition = InStr(1, strContent, "Not all transport requests yet")
If endPosition > 0 then
TRNotReleased = FALSE
Exit for
End If
Next
Next
while when the message comes out, QTP will pop up a window showing "Object Required: objTag(..)", my point is that QTP is not able to find the set object when Web UI changes.
As the message contains different information for each operation, is there any solutions for me to get over from this issue?
Thanks in advance.

Answer 1

When you use objPage.GetElementsByTagName you're getting a reference to a DOM object on the page, this is not a QTP test object but rather an object belonging to the browser. When the DOM in the browser changes the object you're holding onto ceases to be valid.
If you want to access the object after the HTML changes you'll have to ask QTP to retrieve it again. Perhaps like this:
For i = 0 To NumberOfiframe - 1
Set objPage = iframe(i).Object
Set objTag = objPage.GetElementsByTagName("span")
intTotalLink = objTag.Length - 1
For intCtr = 0 to intTotalLink
' Get the collection of objects again
Set objTagCurr = objPage.GetElementsByTagName("span")
Set currObj = objTagCurr(intCtr)