Validations selection screen.

Hi Experts,

In my screen validations . when to use select single and when to use select upto 1 row. and the diffrence.

i hav done the selection screen validations ... now the problem is if the value entered is wrong also the output screen is coming... where if the user is entering wrong value.. it should come back to the selection screen.. not the output screen..

help me in this.

Regards,

Sunita.