Perfect Reconstruction using ISTFT

Hi members,

I am not able to do perfect reconstruction with istft function in matlab. Please see the following functions and point out if I am doing something wrong.

[normStimDB, tDB] = istft(baselineNormDB, EEG.srate, 'Window', sqrt(hann(250, 'periodic')), 'OverlapLength', 125, 'FFTLength', 250);

[timeFreqB2, freqB2, timeB2] = stft(normStimDB, EEG.srate, 'Window', sqrt(hann(250, 'periodic')), 'OverlapLength', 125, 'FFTLength', 250);

The COLA condition is also being satisfied which is required for the perfect reconstruction.