Error using classify!

I am trying to classify training and testing data using "classify" command but unluckily i'm getting an error.

Error using classify

The pooled covariance matrix of TRAINING must be positive definite.

I have following training and testing data:

Training Features with 13320x7 dimensions, where I have 13320 observations and 7 features.

Training Labels with 13320x1 dimensions,

and

Testing Features 106807x7 dimensions, where I have 106807 observations and 7 features

Testing Labels with 106807x1 dimensions.

I have tried PCA, reduced features from 7 to 5, 3 and 1 but it didnt worked.