Compiler Error Message: CS0161: '_Default.parseValue(string, string, string, bool)': not all code paths return a value

hi guys i am getting the above error in my code - below

pleas help me what is wrong in this code as i am a beginner in csharp programming

thanks in advance

public string parseValue(String responseBody, String prefix, String posix, bool include1)
    {
        String action;
        int i;

        //try to find the first type

        i = responseBody.IndexOf(prefix);
        if (i >= 0)
        {
            if (include1)
            {

                action = responseBody.Substring(i);

            }

            else
            {

                action = responseBody.Substring(i + prefix.Length);

            }
            if (!posix.Equals(""))
            {
                action = action.Substring(0, action.IndexOf(posix));
                return action.Trim();

            }
            throw new Exception("Value '" + prefix + "' not found");

        }
    }

add a return action; at the end before the last curly bracket

public string parseValue(String responseBody, String prefix, String posix, bool include1)
    {
        String action;
        int i;

        //try to find the first type

        i = responseBody.IndexOf(prefix);

// The issue is there is not else for this if so there compiler sees it as no return

// value in the case when this condition is not met.
        if (i >= 0)
        {
            if (include1)
            {

                action = responseBody.Substring(i);

            }

            else
            {

                action = responseBody.Substring(i + prefix.Length);

            }
            if (!posix.Equals(""))
            {
                action = action.Substring(0, action.IndexOf(posix));
                return action.Trim();

            }
            throw new Exception("Value '" + prefix + "' not found");
        }

return action; // Or return string.Empty; if you just want a default
}