You need to use #property tester_indicator. Please have a look at this https://docs.mql4.com/basis/preprosessor/compilation:
tester_file, tester_indicator and tester_library properties are necessary for describing the list of the files required for working in virtual hosting.
Indicator files called in iCustom() function with a fixed name, as well as all library files used in MQL4 programs are copied automatically during the migration.
Find out more about migration of programs in the article "How to Prepare a Trading Account for Migration to Virtual Hosting".