Error 7 means that the vi path you use to dynamically load the vi. I attach an example that I have written to demonstrate passing data from a main vi to a dynamically called subvi using queues. As a reference for your programming examine the queue main.vi that calls the dequeue.vi
In general you can use the online help of LabVIEW in order to find out about the meaning of error messages or use the Simple Error Handler.vi from the Time & Dialog palette.
To get the maximum out of LabVIEW I also strongly recommend visiting a LabVIEW trainings course. You could contact your local NI branch for further information.
Best regards,
Jochen Klier Applications Engineering Group Leader National Instruments Germany GmbH