Proper CAN bus termination
The intent of the resistors at each end of the bus is to control transients due to time delays.  The bus needs to be terminated with its characteristic impedance at each end.

However if the bus is only 6 feet long I would expect your implementation with a 60 ohm resistor in the middle to work.  I expect you have some other problem.

You do need to have a device configured to receive the CAN packet and return an ACK to not have an error from the transmitter - some CAN bus monitors do not do so as they are expected to be non-intrusive.  In that case you will get an error from the transmitter if there is no other node.

You may need to put another normal CAN node on the network to get the correct response.