Custom Indicators Setup
Indicators must have been set up before they are used. Working parameters common for all custom indicators (and experts) are set up in the client terminal settings. The corresponding window can be opened by the "Tools — Options" menu command or by pressing of accelerating keys of Ctrl+O. To set up working parameters of indicators, one has to select the "Expert Advisors" tab. Only two options influence working of custom indicators:

Allow DLL imports
Custom indicators can use DLLs to enlarge their functionalities. If this option is enabled, the libraries can be used without any limitations. Disabling of the option results in that no MQL4 program can use any external DLLs.

Allow external experts imports
If there is a need to export functions from other experts or MQL4 libraries during the indicators work, this option must be enabled. If it is disabled, no launched indicator will be able to request for functions from other MQL4 programs.