Without knowing much more about your strategy it is difficult to tell...
You can take a look on
this wiki page, which describes that sometimes an onTick() call can be skipped. Maybe this give some tips.
We also don't know if you have 'missing' tick from the past (data from the cached), or you have issues with 'live' tick, that are being generated. If it is historical data, you can give it a try to clean the platform cache (for VJForex), and delete the cache also for the SDK, so you will download it again.
It is also possible that the SDK and the platform (not sure about VJForex, but the for JForex for sure) are using the same cache, so you will have the same historical data always.
If these tips are absolutely irrelevant, then please provide an example strategy, example outputs, etc, etc, which can help to identify the issue.