Any question answered...

Any problems?

As @Sumo says, it won't do any harm, but if it doesn't hold using Copaslip, then a: it probably won't hold using carbon paste either (the copper granules in Copaslip work in much the same way as the plastic granules in carbon paste in that application) and b: you're trying to paper over a bigger crack, which you should sort out rather than trying to disguise it.