Advice on combo please - SF5

Hi guys,

Haven’t played SF for quite a while but am getting back into it with SF5. My question is very basic - Im trying to do this combo: cr.LK, cr.LP xx HDP. For the life of me I cant seem to cancel properly to get the HDP out. I set the dummy to block after the first attack and every time I do the HDP it either gets blocked (too slow?) or doesnt occur (too fast?). Ive tried to vary the timing on getting the HDP out but not once has it actually hit. Is the timing to get this to work that minute?

Ah, forgot about the link into cancel!!!