This isn't specifically related to measurement studio. Using VB6 and MSIM 14.1. Yes references are set. Multisimapp initialises fine, connects and reads back Version info fine. But, after dimensioning 'CKT' as new interface.multisimcircuit then attempting to read any info from it, I get back 'invalid handle' error and of course CKT is empty, nothing. Tried dim CKT as object, set ckt=msimckt and receive empty set, nothing. Using msim in compatibility mode on win7 x64 platform. Lastly, using annual paid Education Edition (Instructor). Is this a license issue?