MQ4/EX4 are for MetaTrader 4. MQ5/EX5 are for MetaTrader 5. They are not compatible . You cannot run an EX4 file in MT5 or vice versa.
Look at the "Errors" tab at the bottom of the window. mq4 to ex4
Converting is a fundamental step for anyone using the MetaTrader 4 (MT4) platform to build or use custom trading tools. MQ4/EX4 are for MetaTrader 4
This method uses the built-in compiler that comes with every MetaTrader 4 installation. mq4 to ex4
Keep in mind that not all EX4 files can be successfully converted back to MQ4 source code, especially if they were compiled with advanced optimization techniques or encryption.