Probate court says that my moms signed and witnessed will is not good unless i signed it. i am the executor and my name is on the will.

I'm not sure what you mean by the statement that the "will is not good unless I signed it".  Usually the executor does not sign the will and if the will is witnessed and notarized then it should be self proving.  The surrogate's clerks are usually very helpful.  Go back to the clerk that told you about the will and ask what you need to do instead if you can't probate the will.  You made need to go to court by way of a complaint asking for "solemn" probate - meaning you are asking the court to probate a will that is a little irregular