Action Not Being Called When Unchanged Form Submitted

I have a struts application that contains JSP pages with
Next, Previous, and Cancel buttons. My Next and Cancel buttons work great. However, I cannot get the Previous button to invoke the action mapping if NO changes have been typed onto the form. There are actually 2 forms on the page. The first form (not seen below) is included in a header.inc....

Here's a snippet of the JSP:

<form name="Step3Form" method="post" action="/awardBuild/EditAwardDataStep3.do">
<table border="0" cellspacing="2" cellpadding="2">
<tr>
<td width="600" height="2" colspan="4"><img src="images/horizontalbar.gif"/></td>

</tr>
<html:submit styleClass="button" property="<%=Constants.COMMAND%>" value="<%=Constants.EDIT_STEP3%>" ></html:submit>
<html:submit styleClass="button" property="<%=Constants.COMMAND%>" value="<%=Constants.PREVIOUS%>" onclick="document.forms[1].submit();"></html:submit>
<html:cancel styleClass="button"></html:cancel >


I can intercept and trace the EDIT_STEP3 and CANCEL. The previous just re-displays the current JSP, while I need it to invoke the action to determine the next screen to display based on the mapping path. Validator is OFF for this JSP.

Any help is greatly appreciated!