Why are there missing tasks? Why does one go from 6, 7, 8, 9, or 10 to tasks in the 40s? Can you provide us with some insights to this chart?

Task Table Task Name Duration Predecessors Criticality Milestone PERT Chart 45 0 (44) 3 3 2 3 6 7 S.NO. Type Project WBS WBS Legend D Duration M Milestone A Activity C Critical Activity Project Name : ; Building Plastering Initiation Site vat & Area Confirmation Finalisation of Contractor 3 Activity 4.00 days Yes No 4 Activity 7.00 days 3 Yes No 4 5 WBS 7 Plan And Order 3 4 42 6 Activity 0.00 days 4 Yes Yes 4 Mobilisation of Contractor & labor Ordering af Scaffolding members & platforms for Height Works 7 Activity 2.00 days GFS-1 days Yes NO 1 8 Activity Ordering of Cement 1.00 days 655-1 days Yes No 12 8 3 1 Ordering af Sand 1.00 days 655-1 days Yes S No 1 2 1 1 46 47 48 0 49 2 50 51 Activity 10 Activity Ordering of Dust 1.00 days 655-1 days Yes No 41 Execution 3 11 WBS 12 Activity Daily Safety meet 20.00 days No No 9 1 1 3 41 Activity Delivery of Sand, Dust and Cement 3.00 days No SFS+1 Day, 9F5+1 Day. 10F5+1 Day. 7F5-1 Day. 10 3 42 Activity 3.00 days No No 0 0 54 1 2 1 55 56 57 1 58 59 52 43 WBS 44 Activity 3.00 days 6,42 Yes No 0 45 Activity 0.00 days 44 Yes Yes 46 Activity 1.00 days 41 Yes No Delivery of Scaffolding & members at Site Section 1 Setting up of Base & members for scaffolding & Adding on platforms to Top Section Preparation of Mixture Application of Mixture Leveling Fine Casting for Walls and Pillars Irespection for Section 1 Attend Punch Points 60 47 Activity 2.00 days 46 No 48 Activity 1.00 days 47 YA NO 2 49 Activity 1.00 days 49 Yes No 50 Activity 0.00 days see 49 Yes Yes 51 Activity 2.00 days 50 Yes Critical Activity List S.N Type Task Name 0. 3 Activity Site visit & Area Confirmation 4 Activity Finalisation of Contractor 6 Activity Mobilisation of Contractor & labor 7 Activity Ordering of Scaffolding members & platforms for Height Works 8 Activity Ordering of Cement 9 Activity Ordering of Sand 10 Activity Ordering of Dust 41 Activity Delivery of Sand, Dust and Cement 44 Activity Setting up of Base & members for scaffolding 45 Activity Adding on platforms to Top Section 46 Activity Preparation of Mixture 47 Activity Application of Mixture 48 Activity Levelling 49 Activity Fine Casting for Walls and Pillars 50 Activity Inspection for Section 1 51 Activity Attend Punch Points 52 Activity Removal of base & members Setting up of Base & members for 54 Activity scaffolding 55 Activity Adding on platforms to Top Section 56 Activity Preparation of Mixture 57 Activity Application of Mixture 58 Activity Levelling 59 Activity Fine Casting for Walls and Pillars 60 Activity Inspection for Section 1 61 Activity Attend Punch Points 62 Activity Removal of base & members 64 Activity Complete Payment of Works and Close Outward movement for T&P by 65 Activity Contractors 66 Activity Disposal/return of balance material NO 0 S2 Activity 1.00 days 51 Yes No Removal of base & members Section 2 61 62 53 66 WBS 64 54 Activity 3.00 days 52 Ya No 0 0 Setting up of Base & members for scalfolding Adding on platforms to Top Section Preparation of Mixture 54 Yes 55 Activity 56 Activity Yes 0.00 days 1.00 days SS Yes No 65 Application of Mixture 2.00 days 56 Yes No S7 Activity 58 Activity 1.00 days 57 Yes No 59 Activity Leveling Fine Casting for Walls and Pallars Inspection for Section 1 1.00 days 58 Yes No 60 Activity 0.00 days 59 Yes Yes 61 Activity Attend Punch Points 2.00 days 60 Yes NO 62 Activity Removal of base & members 1.00 days 61 Yes No 64 Activity Complete Payment of Works and Cose 0.00 days 62 You Yes 65 Activity Outward movement for T&P by Contractors 0.00 days 62 Yes Yes 66 Activity Disposal/return al balance material 0.00 days 6SFF-1 day Yes Yes