PBRACE from cantilever structure

Dear all,

I am fairly new to the PMEMBER and PBRACE command to do a steel design.

I have been having a problem with checking a cantilever column. I have modeled the column as a single vertical member with a fixed support at the bottom and free end at the top. I have then used the PBRACE command as below. I specify the fixed support to be "FR" and the free end as "U". However, for some reason it doesnt work.

    45. PARAMETER 1
    46. CODE AUSTRALIAN
    47. PBRACE TOP 0 FR 1 U PMEMB 1
    48. PBRACE BOTTOM 0 FR 1 U PMEMB 1
    49. TRACK 2 PMEMB 1
    50. CHECK CODE PMEMB 1
 
   EFFECTIVE RESTRAINT COULD NOT BE FORMED. DESIGN OF THE PMEMBER      1 IS SKIPPED.
 
   DESIGN OF THE PMEMBER      1 IS SKIPPED DUE TO INTERNAL ERROR.
 
 
   ************** END OF TABULATED RESULT OF DESIGN **************

Could someone enlightened me on specifying the the PBRACE for a cantilever PMEMBER?

I used to specify "KY" and "KZ" for checking the cantilever member, i.e. traditional method.

Thanks.