Hello Medha,
Thank you for contacting National Instruments.
From the information you have provided, I am not sure what is causing your problem. Make sure that you do not have an evaluation license for LabVIEW.
What, if anything, was changed in your VI before it stopped working? Will it run without the Matlab script?
If you continue having trouble getting your VI to work, please respond with more information. If you like, you can post your VI (along with any necessary sub-VIs) and I will take a look at it.
Have a great day,
Sean C.
Applications Engineer
National Instruments