Custom Button in SAPLXQQM custom screen (QQMA0001)

Hi Experts,

I checked many threads but remained inconclusive.

I have added one custom button on custom subscreen of notification exit QQMA0001. New subscreen has been created and did config. Now issue is that if i give function code to cutsom button it triggers error 'Requested Function code 'ZU1' is not available' as subscreen cant have its own ok code. So what shall i do, shall i declare fcode in table T185F table ? What shall be approach. I saw few old threads and found that clear sy-ucomm in case of custom fcode that clearing in standard program doesn't seem ok. Can anyone help here.