PIC32 Input Capture Module
Check this command: IFS0bits.IC4IE = 1.
Here IEC0 register should be used IFS0 is used to check the flag bits which get SET when any interrupt occurs. So, modify your command as follows:

IEC0bits.IC4IE = 1


(If it still does not work then check your datasheet for the location of IC4IE bit.)   

IFS0bits..IC4IP = 1 : this command is also wrong , you have to use IPC0 register for setting the priority of the Input Capture.