Reef Crystal IO salt

[Coleus]

Yesterday, I mixed my Ro/di fresh water with Instant Ocean Reef Crystal. Got the salanity to 35ppt (1.026) and temp is 79F and did some water testing. I found the parameter is not what it claims on the bucket

The claim:
Cal : 455ppm
Mg: 1345ppm

Well the result i am getting from my Salifer Test kit is

Cal: 400 ppm
Mg: 1230 ppm

Anyone knows why?

Thanks