This error suggests that you are not using a data format that the block supports. See the Specifying the Workspace Data section of the block's reference page for more information. In addition, the block's dialog provides guidance on how to format matrix or structure data:
For matrix formats, each row of the matrix has a time stamp in the first column and a vector containing the corresponding data sample in the subsequent column(s).
For structure format, use the following kind of structure:
var.time=[TimeValues]
var.signals.values=[DataValues]
var.signals.dimensions=[DimValues]
If you do not actually need time-varying data, then consider using a Constant block instead, where you can enter your data's workspace variable name in the "Constant value" box.
