Error about norm_nuc

Hi, I am trying to use cvx to minimize nuclear norm, the statement is

cvx_begin sdp

variable lowMatx(signalNum,signalNum) symmetric


But I get this error:

Error using class
Cannot change the number of fields of class ‘cvxtuple’ without first typing ‘clear classes’.

Error in cvxtuple (line 19)
v = class( struct( ‘value_’, { v }, ‘dual_’, { [] } ), ‘cvxtuple’, cvxobj );

Error in cvx_end (line 185)
assignin( ‘caller’, ‘cvx_optpnt’, cvxtuple( cvx_collapse( vars, false, false ) ) );

Error in cvx/norm_nuc (line 23)

Error in codeSearch (line 47)

I don’t known why. Could someone help?

I just ran it with no errors and it solved. Can you show a complete MATLAB session starting from scratch? Maybe also MATLAB and CVX version numbers… Not surprisingly, the zero matrix is optimal.