Differential pairs versus Void_Same_Net

Hi guys,

   can you help me with the following problem? I tried to set Void_Same_Net property for the cline, which is a differential pair. But in the command line, I see warning message:

W- (SPMHGE-248): No instances of property VOID_SAME_NET found on the selected element(s). 

 For the normal cline is all right. 

Thank you in advance for your help 

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