A bit confused...need some help again..

Hi,Guys...it's me again...as u know i got 2 GR Puppies....and now i got 1 main problem...i trained both of them to urine at the urine pan already but here is the thing,they urine at the pan but lately both of them sometime urine at the urine pan and sometimes urine every where...why is it so???any thing wrong with them???wat should i do???