Hi everyone, I'm working on a project, to connect 1 s7-300 plc with 2 s7-1200 plc i use this program provided by siemens: https://support.industry.siemens.com/cs/document/40556214?dti=0&lc=en-WW

All PLC are connected via a switch 

I did add some block and change the DB and FB numbers to match with my project, i tested it and it worked fine. After that when my friend add his program into the s7-300 it still worked fine. However when we test it again yesterday, it stopped working. I tried to load the original test program that i included here and it still not working. The s7-300 "Get" instance just output Error and status W#16#0001. The manual  said faulty wiring was caused this problem, however i think the connecting wires is OK since I could online all the plc with TIA portal. I'm confused here, i think maybe my program is wrong? Anyone can help me solve this problem?