I still do not understand exactly what your problem is. Please describe what you want it to do when you get to "the 12 row."
Your queue has a maximum of 16 elements (hex 10). When the queue has 16 elements an attempt to push another element onto the queue will wait forever (default timeout = -1 = never timeout). The VI will freeze in case 1 waiting for an element to be removed from the queue, but the other parts of the code cannot run until the Enqueue completes.
Note that the Pull case (2) has a 1 second timeout so when you attempt to Pull from an empty queue the output string becomes blank after 1 second due to the timeout. You can Push an empty string into the queue and Pull it back out without the 1 second delay.
You should define what the program should do when the queue is full and someone tries to Push and what it should do when the queue is empty and Pull is pressed. Once you define the behavior for those cases, writing the code to do that should be straightforward.
Lynn
