Robots use many coordinate system and for each position you transmit to the robot, it has to be specified in which coordinate system is it defined. If you do not define it explicitly, an implicit definition is used, which may not correspont to the one in which the current postition is defined. So what you think is exaclty near the robot, may be actually out of the operating range.
A simple case is when you give the robots coordinates in its base frame, but it expects realtive coordinates (in tool frame). If the current pose in the base frame is
[1, 0, 0, 0, 0, 0] any you try to reach the coordinates
[1.1, 0, 0, 0, 0, 0], in realtive coordinates you should transmit
[0.1, 0, 0, 0, 0, 0]. The coordinates
[ 1.1, 0, 0, 0, 0, 0] realative to the tool frame are be most probably out of the workspace. (vice versa is also true)
Also check the allowed operation envelope. An incorrect setup of the operation envelope could also cause similar problems.