Function $CS.addOptions doesn't work

Function $CS.addOptions doesn't work

Hi,
I wanted to make a simply script to add an option of choose of one field. script: $CS.addOptions("ServiceReq_1801_UDF_CHAR2",["Piotr","Andrzej","Jerzy"]); 
Unfortunately it doesn't work. For example function: $CS.removeAllOptions(["ServiceReq_1801_UDF_CHAR2"]); works correctly.
Do you know what can be a reason of this?
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