An error has occurred while trying to calculate the tendon effective stresses. A tendon is not connected to any jacks. Investigate tendon #a. [If any tendons are stressed then all tendons must be stressed.]
RAM Concept calculates losses in tendons that have one or two jacks attached. RAM Concept does not allow a (latitude or longitude) tendon layer to have some tendons with jacks but other tendons with no jacks. You can have one tendon layer (say, latitude) with jacked tendons and the other tendon layer with no jacks.
When you encounter this error, find the tendon (from the number given) and draw at least one jack on the tendon.