Error: Message not found (IMMERGEDIMSMISMATCH)
Gridded Item Merge error: Message not found (IMMERGEDIMSMISMATCH)
The gridded items being merged to not have the same grid dimension tags.
Update the item so that the grid dimension tags are the same. Per online help: If the items are gridded, both items must have the same Grid dimension tags (e.g., Color/Size or Color/Size/Width), although the dimension values (e.g., Red, Blue, Yellow) may vary between items). For steps, see KB201.