How to ignore blank values in switch statement

[SBR1D]

Hello

I am using a switch statement which is working fine except for if the result if 0 where it seems to pick up blank values. I have tried adding the ISBLANK function but it does not solve  the problem. 

no date this month / last month / 2 months = SWITCH(

    TRUE, 'Learning Plan'[month since last activity]= 0 , "Activity in this month",

        'Learning Plan'[month since last activity] = -1 , "Activity last month",

        'Learning Plan'[month since last activity] = -2 , "Last activity two months ago",

        iSBLANK('Learning Plan'[month since last activity]), "Last compliance active learning is blank",

        "no data")

[SBR1D]

Thank you very much

[newtodax · Accepted solution]

Try this and let me know if that works for you 

no date this month / last month / 2 months = SWITCH('Learning Plan'[month since last activity],
0, "Activity in this month",
-1, "Activity last month",
-2, "Last activity two months ago",
BLANK(), "Last compliance active learning is blank",
"no data")