Question: Integration with Interpolation package

Strange behavior. I don't know if this can be made to work.  I replaced an equation with an interpolation object, f(x).

tInt := int(f, 133  .. 134, numeric);
tInt := 324.95206944305  <= Computes a result. I

tInt := int(f, 133  .. 312, numeric);
tInt:= int(fproc, 133. .. 312.) <= Won't compute it. The interpolation object has 3051 points, so that's not the problem. The name "fproc" is not something I have in my  code, just the name, "f".

If I try to make the  integral just slightly more complex by  passing a variable in, it doesn't work at all. This was to see if I could integrate with a varying divisor: f(x)/(x+1)
int(f(x), x = 133 .. 134, numeric); 

Error, (in int) wrong number (or type) of arguments: invalid options or option values passed to definite integration. <=

A fallback  was to use summation, but that doesn't work at all, same typ of error as the Error for int. (Not shown.)

So my fallback is to use a for loop to sum the set. The for loops produce another set of values, and I think I have to make interpolation objects for that as well. And so on. I really  was expecting  Maple to handle this better.