EL problem in JSP page, boolean vs. String

Question

We are migrating from WebSphere 6 to WebLogic 11g and are receiving the following error from the JSP pages where we use EL to determine if an element is readonly or not:
The method setReadonly(boolean) in the type BaseHandlerTag is not applicable for the arguments (String)
In doing some testing I can simplify the problem to this:
works (just using EL to set tab index)
jsp:
<c:set var="myTabIndex" value="765" />
<html:text property="user.email" size="28" tabindex="${myTabIndex}" readonly="true" />
source output:
<input type="text" name="user.email" size="28" tabindex="765" value="[email protected]" readonly="readonly">
doesn't work (added EL to set readonly attribute)
jsp:
<c:set var="myTabIndex" value="765" />
<c:set var="myReadOnly" value="true" />
<html:text property="user.email" size="28" tabindex="${myTabIndex}" readonly="${myReadOnly}" />
error output:
userProfile.jsp:60:86: The method setReadonly(boolean) in the type BaseHandlerTag is not applicable for the arguments (String)
<html:text property="user.email" size="28" tabindex="${myTabIndex}" readonly="${myReadOnly}" />
I'm not sure what is going on here and have spent two days researching this and trying different things to no avail. I don't believe any casting should be necessary. I thought for a while EL was not enabled but in my working sample EL is being used to determine tab index. The 'does not work' code works ok in WebSphere 6 and Tomcat 6, so it is just WebLogic we are having an issue with.
Thanks in advance for any help that can be provided.
Michael

Answer 1

Found more output in the log file that might be helpful (this is output from the real code, not the sample code I mentioned previously):
weblogic.servlet.jsp.CompilationException: Failed to compile JSP /WEB-INF/modules/ContactTile.jsp
ContactTile.jsp:241:17: The method setReadonly(boolean) in the type BaseHandlerTag is not applicable for the arguments (String)
readonly="${displayonly}"
^--------------^
at weblogic.servlet.jsp.JavelinxJSPStub.reportCompilationErrorIfNeccessary(JavelinxJSPStub.java:226)
at weblogic.servlet.jsp.JavelinxJSPStub.compilePage(JavelinxJSPStub.java:162)
at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:256)
at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:216)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:243)
Truncated. see log file for complete stacktrace
Michael