Ah, didn't realise you were using the EEL version. As Argitoth has noted there are no 'True' and 'False' constants in EEL so you need to use 1 or 0 for those in converted scripts. If you just want to open/create an instance of SPAN on the master you'd do this...
Code:
ShowNamedPlugin("SPAN", GetMasterTrack(0), 1);