Transceiver link connection error

Hello, I'm a beignner of Quartus II tools.

Now I'm using a Stratix V and the transceiver toolkit function.

But there was an error of transceiver links while I'm measuring BER.

The error script in tcl command window was as follows,

"error: alt_xcvr_reconfig_eye_viewer_set_vertical_step: null"

The transceiver link suddenly stopped in a for loop (controlled by a tcl script) with the error.

I couldn't figure out that reason of the error.

Attached is the figure of the link status.

Can anyone help me?

Thank you

Insun Shin