DLL file integration with MATLAB for custom USB

I want to make a GUI which can take data from a custom USB device and plot it on the chart. Basically, where I am stuck is the DLL file section. I have made a DLL file from Visual Studio Environment, I have tested the custom USB device with visual studio. On integrating it with MATLAB using a command to call DLL file, I am unable to see methods that were defined in the DLL. FYI, I have been able to integrate this DLL file with LABVIEW. Please help me to achieve this task of mine.

[Kaustubha Govind]

Please paste what MATLAB command you are using to look at the exported functions in the DLL, and how exactly the functions in the DLL are exported (from the header file of the library).