NAnt properties created by other tasks not recognized

I'm getting "unkonwn property" errors for properties that are created by a task other than "property". For example, the following:

<loadfile file="$" property="versionText" />
<regex
input="$"
pattern="(?'searchText'(?'majorVersion'[0-9])\.(?'minorVersion'[0-9])\.(\*|\.[0-9]))"
/>

<property name="newVersion" value="$" />

<property name="newVersionText" value="$" />

Gives "unknown property" errors on versionText, majorVersion, minorVersion, and searchText. All of these are valid properties.

Thanks,

Sam