I tried to edit the CloudMap EMS workflow based on my own data. But I failed to make a connection between "Select Variants" and "SnpEff". In fact, I failed to reconstruct the connection between them even when I removed the original one by clicking "x" when moved cursor on the line. The arrow on left of SnpEff does not become green when I drugged the line from output_vcf(vcf) to it after I moved the original one. Could you tell me why does this happen and how should I figure this out? 

Thanks a lot!

Best

Xiaofei