Why matlab shows the error like >> INI_PHASE must be a real scalar ?

Here I have used the Loop>> refConst = qammod((0:63).', 64,'UnitAveragePower', true); Matlab shows the error in >> refConst = qammod((0:63).', 64,'UnitAveragePower', true); like>> INI_PHASE must be a real scalar and why?

[Walter Roberson]

Duplicated by later https://www.mathworks.com/matlabcentral/answers/363233-why-matlab-shows-an-error-like-error-using-qammod-line-54-ini_phase-must-be-a-real-scalar which has an answer