disable PRINT function in sapscript.

hi everyone, could anyone let me know how do i disable print function if there's error occured.

ive set as below not to allow print preview and print via print preview.

itcpo-tdpreview = ' '.

itcpo-tdnoprint = ' '.

however although i've set it, i still able to print my form.

how do i acheive my objective above?

thank you.

regards,

sw