When an entry in the Predecessors column cannot be used, the link is not drawn and the Issues panel names the row and the entry. Click the issue to go to the cell.
Unknown reference #
SimpleGantt looks up a reference in this order: the ID column, then the WBS number, then the task name. Only a table without an ID and a WBS column uses the row number within the data (the first task row is 1). Common causes when nothing matches:
- No ID column, and the number refers to an Excel row number (such as 12) instead of the task’s position in the table. Add an ID column, or use the task’s position.
- An ID or WBS column exists, but the reference is a row number. With either column, numbers are matched against it, not against row positions. Use the task’s ID or WBS number.
- The row was sorted or deleted. Row numbers move; IDs do not. An ID column prevents this.
- A task name with a space or comma is split into two references. Put the name in quotes: “Design review”.
- A typo in the link type. Valid types are FS, SS, FF and SF, and lags end in d, w, h or %, for example 3FS+2d. See Link tasks with dependencies and lags.
- Text versus number. An ID stored as text (“1”) and one stored as a number (1) are treated as the same; if a match still fails, check for extra spaces.
Circular dependency #
Task A waits for B, and B (directly or through other tasks) waits for A. The Issues panel names the tasks in the loop. Remove one of the links in the loop; until then, the links in the loop are not drawn.
Other messages #
- Refers to itself: the row lists its own ID. Remove it.
- Duplicate ID: two rows share an ID. References use the first one; give the second a unique ID.
- Link to a folded task: not an error. The arrow is drawn to the summary bar while the phase is collapsed.
In the free version, dependencies are read but arrows are not drawn. That is not a missing predecessor.