String - Formula

Hello,

I have a field which is a string variable here.

I need to eliminate the word Slow in my display here, also to throw into the mix there are blanks/null values here also.

I have tried record expert to <> "Slow" but then it will also not display the null values here.

So I am in Formula Workshop and I trying to build some there here.

Here is what I have, but it's not working:

if IsNull({V_INV_MSTR.HAZARDOUS_MATL_CODE})  or ({V_INV_MSTR.HAZARDOUS_MATL_CODE} <> "SLOW") then

{V_INV_MSTR.HAZARDOUS_MATL_CODE}

else

{V_INV_MSTR.HAZARDOUS_MATL_CODE}

With this code it's still showing the SLOW word and I don't need it.

Any help would be appreciated.

Thank you,
Gerald