replace string function

Hi,

Right now, I'm trying to use the replace String function with my form but for some reason, I'm not getting the result that I desire.

For example, here is my code below

form1.variables.x.value = "ABAA";

form1.variables.x.value = String.replace(form1.variables.x.value,'A','x');

AMLSummary.rawValue = form1.variables.x.value;

When I output AMLSummarY (which is a textfield), the answer I'm expecting to be is "xBxx".

However, the result I'm getting is "xBAA".

Does anyone know why? Much appreciated. Vince