Hi Naval, I agree with Walter that we need more information. It helps to give us some sample data that we can reproduce the issue from. However, I will just guess that the problem is pskmod() does not accept inputs that are not positive integers. When you obtain the wavelet transform of some positive integer-valued data, you are certainly not guaranteed to obtain positive integer-valued coefficients. In fact, you are likely not going to obtain integer-valued coefficients.
The Haar transforms, haart(), have an 'integer' option that will ensure that the wavelet coefficient outputs are integers, but you will still not be assured that those integers will be positive.