The criteria include account name (whose private key it is associated with), domain, company, expiration date, intended purposes, among other things.
There are many different possible reasons for this error to occur, some have been listed already. Here is another tip: When importing a certificate, be sure you work with the original file received from the certificate authority (CA), or else some of the properties might be lost.
Example: recently I tried to import a certificate exported from a different account on the same machine. The certificate became visible to my account but was not associated with my account, and as a result signtool refused to recognize it without explicitly providing the file name and a password. Which, when done as part of the build process and written out explicitly in a batch file or source file, may not be sufficiently secure. (Importing the original CA-issued certificate solved it.)