Image Classification Labelling Error:

I am going through Image Classification Model and I am almost done with it,

But I am stuck in labeling the sample data, I have images in 4 categories and so I'm using to_categorical to label the data,

and I am getting this error ...

InvalidArgumentError: logits and labels must have the same first dimension, got logits shape [20,1] and labels shape [100]

If someone can help me with this ....

Thanks in advance.