In the typical case of Lumley v Gye liability, the defendant persuades the third party to break his contract with the claimant, the breach of contract is clear and unequivocal, and no issue arises thereon.
On the other hand, where the third party's act is not a breach of contract or other actionable wrong, then the defendant incurs no liability simply for instigating that act. So the defendant cannot be liable under Lumley v Gye for persuading the third party not to enter a contract in the first place (Midland Cold Storage Ltd v Steer [1972] Ch 630, [1972] 3 All ER 941,