Error in Correlation Coefficient

I was trying to use the quick measure to get the Correlation Coefficient but getting this error below.

category is STDID

X-Axis  is AttendanceRate

Y-Axis is GWA

Error Message:
MdxScript(Model) (230, 3) Calculation error in measure 'Correlation_Coefficient ( Including 0 )'[Average of STRATTENDANCERATE and Average of strFinalGWA correlation for FullName]: An argument of function 'SQRT' has the wrong data type or the result is too large or too small.

My Initial conclusion (which not totally sure) is data type mis match since my GWA is example. 1.5, 1.25, 1.33 etc. 

and my attendance rate is 98.00, 87.00, 99.44 

and bunch of blanks both in GWA and AttendanceRate

Any workaround to resolve the error?

Should I remove those blanks affecting both GWA and AttendanceRate? 

Appreciate the help a lot!

My Table shows like this: 

Sample Data