You don't explicitly supply a number of the .replace parameters and perhaps the wrong ones are being assumed?
From help:
"The settings for LookAt, SearchOrder, MatchCase, and MatchByte are saved each time you use this method. If you don’t specify values for these arguments the next time you call the method, the saved values are used. Setting these arguments changes the settings in the Find dialog box, and changing the settings in the Find dialog box changes the saved values that are used if you omit the arguments. To avoid problems, set these arguments explicitly each time you use this method."