Registry plugin - writeExtra

I'm unable to writeExtra to a REG_MULTI_SZ value... I keep getting a -1 return code and the value is not being appended to. What's wrong with this statement?

${registry::WriteExtra} "SYSTEM\CurrentControlSet\Services\TlntSvr" "DependOnService" "Fax" $rc

Thanks in advance,
Chris

Nevermind!

I see I didn't have the full path.