Pusblishing to topic problem (Mavros)

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I'm trying to push to the override RC for mavros.

I checked the message type first rostopic type mavros/rc/override giving mavros_msgs/OverrideRCIn

I then check the parameters for this message type rosmsg show mavros_msgs/OverrideRCIn giving uint16 CHAN_RELEASE=0 uint16 CHAN_NOCHANGE=65535 uint16[8] channels

however, when I try to publish with rostopic pub /mavros/rc/override mavros/OverrideRCIn "channels:[1500, 1500, 1500, 1500, 1325, 1560, 2000, 1500]" it gives the following error ERROR: invalid message type: mavros/OverrideRCIn. If this is a valid message type, perhaps you need to type 'rosmake mavros'

am I passing the arguments wrong?