How to use Assert.Equal() with decimal numbers

Question

I have to create unit tests for a convert UoM class, which has decimal values as input and output values. Is there any specific with using decimal numbers with Assert.Equal()? My test fails with this error: "Message: Assert.AreEqual failed. Expected:<0.2690288718 (System.Decimal)>. Actual:<0.26902887 (System.String)>."

This is the test:

[TestMethod]
        public void ValidateConversionKG_FTtoKG_M()
        {
            decimal actualValuetoConvert = 0.082M;
            string actualFromUnit = "kg/ft";
            string actualToUnit = "kg/m";
            var actualResult = ESPv2MigrationTool.CommonTools.Utils.ConvertDecimalToString(ESPv2MigrationTool.CommonTools.Conversion
                .LinearWeightUnitConvert(actualValuetoConvert, actualFromUnit, actualToUnit));
            decimal expectedResult = actualValuetoConvert * 3.2808399M;

            Assert.AreEqual(expectedResult, actualResult);
        }

And here is the LinearWeightUnitConvert method:

 public static decimal LinearWeightUnitConvert(decimal valueToConvert, string fromUnit, string toUnit)
        {
            //kg/m, lb/in, oz/in, g/m

            if (fromUnit.ToUpper() == "KG/M")
            {
                if (toUnit.ToUpper() == "KG/M")
                    return valueToConvert;

                if (toUnit.ToUpper() == "LB/IN")
                    return valueToConvert * 0.0559974146M; //86.79617M
                if (toUnit.ToUpper() == "OZ/IN")
                    return valueToConvert * 0.895958634M; //1388.73866M

                if (toUnit.ToUpper() == "G/M")
                    return valueToConvert * 1000;
            }

ESPv2MigrationTool.CommonTools is the namespace and this is a part of the ConvertDecimalToString method of the Utils class:

public static decimal ConvertStringToDecimal(String inputValue)
        {
            string localValue = null;
            decimal decValue = 0.0M;
            try
            {
                if (!string.IsNullOrEmpty(inputValue))
                {
                    decValue = Decimal.Parse(inputValue, System.Globalization.NumberStyles.AllowExponent | System.Globalization.NumberStyles.Float);
                    localValue = decValue.ToString("#0.########", CultureInfo.InvariantCulture);
                }
            }

And this is where the whole conversion method is invoked:

internal static string ConvertValueOfLinearWeight( DataRow dataRow, EED_Data eedData)
        {
            decimal value = 0.0M;
            if (!string.IsNullOrEmpty(dataRow[HeaderID.LineicWeight].ToString()))
            {
                value = Utils.ConvertStringToDecimal(dataRow[HeaderID.LineicWeight].ToString());
            }

            var fromUnit = CommonMapping.GetUnit(dataRow[HeaderID.DivisionManagementUnit].ToString());
            var toUnit = CommonMapping.GetEedLinearWeightUnit((Units)eedData.Items[0]);

            return Utils.ConvertDecimalToString(Conversion.LinearWeightUnitConvert(value, fromUnit, toUnit));
        }