[Solved] C# String Replacement not working [closed]

by 


string oldValue= "iif([PricingTKt_US]>0,1-([F221-B01]/iif([PricingTKt_US]=0,1, [PricingTKt_US])),0)";

PricingTKt_US Capital K.

oldValue=oldValue.Replace("[PricingTkt_US]","[F123]")

PricingTkt_US Small k

solved C# String Replacement not working [closed]