This error occurs if you attempt to read from a shared variable that is set to write only.

Note   If you create a Shared Variable node for a variable that is set to write, the node has an input and can read from other objects on the block diagram. The Shared Variable node is set to read.

To correct this error, right-click the Shared Variable node and select Change To Write from the shortcut menu, or configure the shared variable to allow read access.