Problem dissolving sodium phosphate dibasic heptahydrate? - (Apr/05/2016 )

Has anyone ever had a problem dissolving sodium phosphate dibasic heptahydrate? I'm using ddH2O as solvent and final concentration should be 0.5 M, which doesn't seem that concentrated to me.

I haven't but according to Santa Cruz, http://www.scbt.com/datasheet-203402-sodium-phosphate-dibasic-heptahydrate.html, you're out of the solubility range at 0.5M.  It states a solubility of 100g/L (0.37M).  Can you make a 0.3M stock instead?