Scheduling Dates in SAP-PS

Hi fellows,

At present I have the following Work Plan, I don´t have any constraints in dates

Now, I need rescheduling the activity "Drawings", before this activity had a duration of 9 days, now the new duration is 4 days, after that I programmed and I got this Work Plan,

Now with that programing, I have the followings problems:

- The critical path is not correct

- The calculation is bad, because the activity "Civil Activities" must start in 27/01 and not 30/01

Thanks in advance