That's probably because your machine.config is telling asp.net that the
Blackberry browser only supports WML, or at least that's what it is
defaulting to.

When the asp.net 1.1 mobile controls came out, there was supposed to be
continuing updates to the <browserCaps> to support many different kinds of
devices, but that never seemed to materialize and then asp.net 2.0 went off
and handled mobile devices in a different way.

Try this:

1) In addition to the settings I gave before for the Blackberry browser,
make sure it is set to render HTML & WML.  It's another option in the same
screen as the other options.  It's probably already the default, but double
check.  Also make sure the emulation is set to Blackberry.  (If you are
using a BES, you can create a policy for your users and push out the policy
so all of the devices have these options set for running your mobile app.)

2) Open Notepad, paste the lines below (between the ==== lines) into
Notepad, and save the file as
C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\CONFIG\blackberry.config

3) Edit the file
C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\CONFIG\machine.config and
search for the <browserCaps> line.  Just under it should be a "<result
type=" line.   Below the "<result type= line", add this line:

     <file src="blackberry.config" />

You might need to do an iisreset after doing this - I forget if that is
necessary or not.

These changes will tell the asp.net 1.1 mobile controls that the Blackberry
can do things like html, javascript, tables, etc. and should make it render
correctly.

===================================
<?xml version="1.0" encoding="utf-8"?>
<browserCaps>
 <use var="HTTP_USER_AGENT" />
   <filter>
<case match="BlackBerry.*">
        IsMobileDevice = "true"
 isColor = "True"
 javascript = "True"
 breaksOnInlineElements = "False"
 browser = "mobile browser"
 canInitiateVoiceCall = "True"
 canSendMail = "True"
 cookies = "True"
 inputType = "keyboard"
 maximumHrefLength = "1000"
 maximumRenderedPageSize = "100000"
 mobileDeviceManufacturer = "RIM"
 mobileDeviceModel = "RIM 7520"
 preferredImageMime = "image/gif"
 preferredRenderingMime = "application/xhtml+xml"
 preferredRenderingType = "html32"
 requiresAbsolutePostbackUrl = "False"
 requiresCommentInStyleElement = "True"
 requiresFullyQualifiedRedirectUrl = "False"
 requiresHiddenFieldValues = "False"
 requiresHtmlAdaptiveErrorReporting = "False"
 requiresOnEnterForwardForCheckboxLists = "False"
 requiresPostRedirectionHandling = "False"
 requiresXhtmlCssSuppression = "False"
 screenBitDepth = "24"
 screenCharactersHeight = "9"
 screenCharactersWidth = "33"
 screenPixelsHeight = "160"
 screenPixelsWidth = "240"
 supportsAccessKeyAttribute = "False"
 supportsBodyClassAttribute = "True"
 supportsBodyColor = "True"
 supportsBold = "True"
 supportsCss = "True"
 supportsDivAlign = "False"
 supportsDivNoWrap = "False"
 supportsEmptyStringInCookieValue = "True"
 supportsFontColor = "True"
 supportsFontName = "True"
 supportsFontSize = "True"
 supportsItalic = "True"
 supportsNoWrapStyle = "False"
 breaksOnInlineElements = "false"
 supportsQueryStringInFormAction = "True"
 supportsRedirectWithCookie = "True"
 supportsSelectFollowingTable = "True"
 supportsStyleElement = "True"
 supportsTitleElement = "True"
 supportsUrlAttributeEncoding = "True"
 tables = "True"
</case>
   </filter>
</browserCaps>
=================================