Synopsis
Where you were supposed to supply a whole number (ie, integer) as the loop count for a FOR or DO instruction, you supplied either a non-numeric number, or one containing a fractional component (for example, 1.5).
Cause
You specified a variable name whose value is intended to be the loop count, but that variable's value is not numeric, or contains a fractional component.
Cure
Make sure the variable's value contains only the digits 0 to 9.