Using an alias to a port + pin is fine for some operations, but what tenaja told you is 100% correct. You cannot use anything except ADCIN 0,VAR - or ADCIN 1,VAR, etc.

The 0,1,2,3,4, etc immediately after the ADCIN command is a constant. Not an alias to a PORT + PIN. This should be fairly clear by simply reading the manual, and looking at the example provided - or searching this forum for ADCIN examples.