[ URGENT ] Add Specific WCFM Weight Based Custom Shipping Rules

i want to add following weight based shipping rules. 1st KG – Rs.300 additional more Rs.50 per 1KG by custom shipping rule since this rule is not supported by WCFM. Im using WCFM shipping.

1 KG <= Rs. 300, 1KG >= Rs.50/KG

apply_filters( 'wcfmmp_shipping_weight_calculate_amount', function( $total_weight, $amount){
	if ($total_weight <= 1){
		$amount = 300;
	}
	else ($total_weight > 1){
		$amount = ($total_weight - 1 * 50) + 300;
	}
}

I made this code, but i cant find what the error is, please guide me