Blackbody Intensity Plot


My objective is to plot the blackbody spectrum and also find out the integral value for a defined limit. However, I am getting the following constant value of Blackbody intensity and also getting an error message while calculating the radiated power. Therefore, it would be great if anyone can suggest me how to solve the problem. Here is the expression for dataInt. I am unable to attach the data file here. So, please let me know if it is required to be uploaded.

dataInt =  Interpolation[Table[{data[[i, 1]], data[[i, 2]]}, {i, 1, N1}], InterpolationOrder -> 1]; 

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