Set value in repeating section

[WC]

I have textbox1 in a repeating section and a non-repeating textbox2. Through
OnAfterChange, I want to append textbox2's value after the textbox1's value.
For example, "text1 text2". I haven't been successful setting a rule in
textbox1 as I get this error:
The number of calls to the OnAfterChange event for a single update in the
data exceeded the maximum limit.

I've tried adding code to the OnAfterChange but to no avail...same error
message. I would greatly appreciate any guidance.

function msoxd_my_frmHeading::OnAfterChange(eventObj)
{
var oHeading =
eventObj.Source.parentNode.selectSingleNode("../my:frmHeading")
var oAuthor = XDocument.DOM.selectSingleNode("//my:myFields/my:frmAuthor")
oHeading.text += " (" + oAuthor.text + ")";
}