Hi @sunyaer,
You can replace one or more items within a dynamic array.. - I believe that's what happened in your file, one of the lines was replaced with a shorter one..
1- Create any object - say a circle (or a shorter line
2- Select the array..
3- In contextual tab callled "Array" that appears go to "Options" Panel and select "Replace Item"
- Now select the new item (or items) you drew ( circle, line..) + enter
- Select the base point of that object that will reside on the array path..
- Now select the items to replace within the array..
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Dwg attached..