Don't panic, let see the possibilities...!
- How old you thing the PR and the hardener is...???
- What is the factory reccomended hardener percentages to be use with that PR...???
- Are the dyes liquid or powder...???
- Is the casting composed with PR only (and dyes) or also something else (wood, etc..)...???
- Are you using a pressure pot...???
- What is the ambient temperature and moisture % of where you made and keep your castings...???
It is possible and most plausible that, the answer is within one or more of these questions, at first glance, it seems that you didn't add enough hardener but, until I know that the factory recommendations are, I can't be sure.
I'm sure "we" will find the right answer...!
Cheers
George