Please post your original code. The express VIs you show can have multiple configurations, and the configuration you chose will determine what the problem is. That said, I speculate that you chose the LVM file format, which is a text-based, tab-separated file designed for easy reading into a spreadsheet. If you stream data using that format, the data is saved as segments. Each segment is separated by a header giving acquisition information for the segment. If you use the Read From Measurement File Express VI to read from this file, it will read one segment every time you call it, not the entire data set. You need to call the VI in a loop and it will read the segments as they were written. You can open LVM files in any text or spreadsheet editor and look at them (e.g. Notepad++, VIM, Excel, LibreOffice Calc).
If you have further questions, please ask.
. 
