An array constant or a cluster constant on the block diagram has no elements. LabVIEW does not know what the array or cluster constant data type should be.
Complete the following steps to correct this error.
Add typed constant elements to the array or cluster constant.
Click the Show Error button in the Error list window to find the empty array or cluster constant. LabVIEW indicates untyped arrays or cluster constants by coloring them black.
Place a typed constant inside the array or cluster constant by moving an existing constant on the block diagram or by selecting one on the Functions palette. LabVIEW changes the color from black to the color of the new data type.