!NO_DATA! is an IQFeed message that means there is no market-depth data for this symbol. It is my understanding that Market Depth information is only available for futures and equities (not options), and only on some exchanges, and only if you are subscribed to the necessary IQFeed entitlement(s).
Consider using my IQML (IQFeed-Matlab) connector as an alternative. IQML enables both synchronous (blocking) and asynchronous (background) queries, that are fetched either serially or in parallel (using the Matlab Parallel Computing Toolbox). A simple usage example:
data = IQML('marketdepth', 'symbol','@ES#');
IQML was developed with top performance, reliability and usability in mind. IQML supports 100% of IQFeed's API functionality. It is fully documented, continuously maintained/improved, and I am happy to provide support.
Note: I am an independent software developer and not a MathWorks employee. Don't get angry at me for bringing an independent alternative to the table...