Missing Data?

Does anyone know the technical aspects to how MT4 works ? My 1 minute charts looks to me like it has incomplete data I dont think that many candles would have no tails on them.
I was wondering if the data displayed on other timescale charts is extrapolated from the data on the 1 minute charts and if so wouldnt the missing data on the 1 minute charts mean the 5 minute charts would not be reliable and therefore the 15 minute charts even worse etc ?

http://i936.photobucket.com/albums/ad201/SDCforex/Capture.jpg