"ServerID must be a string" problem

I can not read the data from the dialogue box to connect the OPC server. The error occurs: "ServerID must be a string"

Here's the code:

 function Newhost_Callback(hObject, eventdata, handles)
prompt = {'Host name:'};
dlg_title = 'Input';
num_lines = 1;
defaultans = {'Matrikon.OPC.Simulation.1'};
answer = inputdlg(prompt,dlg_title,num_lines,defaultans);
da = opcda('localhost', answer);
connect(da);

Answer 1

[Walter Roberson]

inputdlg() always returns a cell array, not a single string.

da = opcda('localhost', answer{1});

[Nikolay Panasetsky]

Thank you)