The trial version does have all the same features as the full version, but unmanaged profiling is just not supported for .NET 1.1 applications, I'm sorry to say.
I can't seem to find this in our documentation at the moment--my apologies for that! I'll request that this information be added.
(Just a note: The "Objects that are / are not disposed" filter is also not available for .NET 1.1 apps. More details here