Something not wired up in your block diagram? A subVI is getting an empty string rather that the data you have showing in the control.
Post your VI so we can look at it.
You might wind up having problems because you are trying to use two different DAQmx channels in two different tasks. Normally that would cause a resource conflict.
But I think your current problem is the controls you have wired up to the create task. If you notice, some of the clusters have coercion dots which means the control going into doesn't match the datatype the subVI is expecting. Delete the wire going in, and recreate the control from the terminal of the subVI (Right click Create Control). You'll see the clusters are different and that the items in the cluster are in a different order than your original control.
Thank you for correct suggestions but now there is another issue that is terminal connection. Summary how can i connect the 2 wire 120 ohm strain gage to 1520. Please look at attached file for detail.
All gages are technically 2-wire. What makes a 3-wire gage is adding another wire to one of the sides.
So add another wire to one side of the gage that is the same length and wire size as the leads already on your gage.