Invalid type in subtraction Operator

[Kinetic_analytics]

Hello:

How may I fix this error?

Thanks

[binuacs]

@Kinetic_analytics 

IIF([Date]> [Yesterday],Null(),1+((DateTimeDiff([Yesterday],[Date],"days")* 5 -([StartWeekdays] -[EndWeekDays]) * 2)/7) + (IIF([EndWeekDays] ==6,-1,0)+IIF([StartWeekdays]==0,-1, 0)))

Spoiler

[Qiu]

@Kinetic_analytics 
It seems that the column [EndWeeksDays] is a string type, which should be numeric type.

Can you kindly provide a data sample set?

[Kinetic_analytics]

Thank you.