Some strange errors

Hi, I'm working on a programming project (for a course), where I have a class that represents a resistor, and takes the color bands as input and outputs the resistance/tolerance, and vice versa. It's not completed, and I was just testing the function that took the color bands and outputted the resistance and tolerance, and got a bunch of errors. My code:

#include <iostream>

#include <string>

#include <sstream>

using namespace std;


class Resistance

{

    private:

        double resistance;

        int tolerance;

        string BandA;

        string BandB;

        string BandC;

        string BandD;

    public:

        int Find_Resistance(string,string,string,string,double&,int&);

        int Find_Bands(double,int);

        void Find_RMaxMin(double&,double&);

}

int Resistance::Find_Resistance(string band1, string band2, string band3, string band4, double &res, int &tol)

{

    BandA = band1;

    BandB = band2;

    BandC = band3;

    BandD = band4;

    if ( BandB == "black" ) resistance = 0;

    else if ( BandB == "brown" ) resistance = 1;

    else if ( BandB == "red" ) resistance = 2;

    else if ( BandB == "orange" ) resistance = 3;

    else if ( BandB == "yellow" ) resistance = 4;

    else if ( BandB == "green" ) resistance = 5;

    else if ( BandB == "blue" ) resistance = 6;

    else if ( BandB == "violet" ) resistance = 7;

    else if ( BandB == "gray" ) resistance = 8;

    else if ( BandB == "white" ) resistance = 9;

    else return 2;

    if ( BandA == "black" );

    else if ( BandA == "brown" ) resistance += 10;

    else if ( BandA == "red" ) resistance += 20;

    else if ( BandA == "orange" ) resistance += 30;

    else if ( BandA == "yellow" ) resistance += 40;

    else if ( BandA == "green" ) resistance += 50;

    else if ( BandA == "blue" ) resistance += 60;

    else if ( BandA == "violet" ) resistance += 70;

    else if ( BandA == "gray" ) resistance += 80;

    else if ( BandA == "white" ) resistance += 90;

    else return 1;

    if ( BandC == "black" );

    else if ( BandC == "brown" ) resistance *= 1E1;

    else if ( BandC == "red" ) resistance *= 1E2;

    else if ( BandC == "orange" ) resistance *= 1E3;

    else if ( BandC == "yellow" ) resistance *= 1E4;

    else if ( BandC == "green" ) resistance *= 1E5;

    else if ( BandC == "blue" ) resistance *= 1E6;

    else if ( BandC == "violet" ) resistance *= 1E7;

    else if ( BandC == "gray" ) resistance *= 1E8;

    else if ( BandC == "white" ) resistance *= 1E9;

    else if ( BandC == "silver" ) resistance *= 1E-1;

    else if ( BandC == "gold" ) resistance *= 1E-2;

    if ( BandD == "gold" ) tolerance = 5;

    else if ( BandD == "silver" ) tolerance = 10;

    else if ( BandD == "none" ) tolerance = 20;

    else return 3;

    res = resistance;

    tol = tolerance;

    return 0;

}

int Resistance::Find_Bands(double res, int tol)

{

    if ( res >= 100000000 || res <= 0.01 ) return 1;

    if ( tol != 5 || tol != 10 || tol != 20 ) return 2;


}

void Resistance::Find_RMaxMin(double &min, double &max)

{

    min = resistance - resistance * tolerance / 100.0;

    max = resistance + resistance * tolerance / 100.0;

}

void decapitalize(string &in)

{

    stringstream stream;

    char temp;

    int length;

    length = in.length();

    stream << in;

    in.clear();

    for ( int i = 0; i < length; i++ )

    {

        stream >> temp;

        if ( temp < 97 ) temp += 32;

        in += temp;

    }

}

int main()

{

    double r;

    int t;

    double RMax;

    double RMin;

    string band1,band2,band3,band4;

    int option;

    Resistance resistor;

    cout << "Enter the first color band: ";

    cin >> band1;

    cout << "Enter the second color band: ";

    cin >> band2;

    cout << "Enter the third color band: ";

    cin >> band3;

    cout << "Enter the forth color band: ";

    cin >> band4;

    decapitalize(band1);

    decapitalize(band2);

    decapitalize(band3);

    decapitalize(band4);

    resistor.Find_Resistance(band1,band2,band3,band4,r,t);

    cout << "Resistance: " << r << endl;

    cout << "Tolerance: " << t << endl;


}

The error log:

N:\EGR125summer10\Project2\Project2.cpp|21|error: new types may not be defined in a return type|

N:\EGR125summer10\Project2\Project2.cpp|21|error: extraneous `int' ignored|

N:\EGR125summer10\Project2\Project2.cpp|21|error: prototype for `Resistance Resistance::Find_Resistance(std::string, std::string, std::string, std::string, double&, int&)' does not match any in class `Resistance'|

N:\EGR125summer10\Project2\Project2.cpp|16|error: candidate is: int Resistance::Find_Resistance(std::string, std::string, std::string, std::string, double&, int&)|

N:\EGR125summer10\Project2\Project2.cpp|21|error: `Resistance Resistance::Find_Resistance(std::string, std::string, std::string, std::string, double&, int&)' and `int Resistance::Find_Resistance(std::string, std::string, std::string, std::string, double&, int&)' cannot be overloaded|

N:\EGR125summer10\Project2\Project2.cpp||In member function `Resistance Resistance::Find_Resistance(std::string, std::string, std::string, std::string, double&, int&)':|

N:\EGR125summer10\Project2\Project2.cpp|36|error: conversion from `int' to non-scalar type `Resistance' requested|

N:\EGR125summer10\Project2\Project2.cpp|47|error: conversion from `int' to non-scalar type `Resistance' requested|

N:\EGR125summer10\Project2\Project2.cpp|63|error: conversion from `int' to non-scalar type `Resistance' requested|

N:\EGR125summer10\Project2\Project2.cpp|66|error: conversion from `int' to non-scalar type `Resistance' requested|

||=== Build finished: 9 errors, 0 warnings ===|

It looks to me that the compiler thinks I declared Find_Resistance as Resistance class, when I actually declared it as an int.
BTW, I know my coding isn't the best, like using int return types to return errors, but I'm just following directions, so please don't suggest improvements to error checking, etc.