Java Programming

i got this error:

ERROR [org.hibernate.proxy.BasicLazyInitializer] CGLIB Enhancement failed: my.com.shinyang.ilms.model.MCurrency
java.lang.IllegalArgumentException: Superclass has no null constructors but nopackage my.com.shinyang.ilms.model;

import java.util.Date;

import my.com.shinyang.ilms.ui.table.TableData;

public class MCurrency implements java.io.Serializable, TableData {


    // Fields         private String code;
     private int rate;
     private String description;
     private int unit;
     private Date fromDate;
     private Date toDate;
         // Constructors

    public MCurrency(String code, String description, Date fromDate, Date toDate, int rate, int unit) {
    this.code = code;
         this.description = description;
         this.rate = rate;
         this.unit = unit;
         this.fromDate = fromDate;
         this.toDate = toDate;
    }

/** minimal constructor */
    public MCurrency(String code) {
        this.code = code;
    }

public String getCode() {
return code;
}

public void setCode(String code) {
this.code = code;
}

public String getDescription() {
return description;
}

public void setDescription(String description) {
this.description = description;
}

public Date getFromDate() {
return fromDate;
}

public void setFromDate(Date fromDate) {
this.fromDate = fromDate;
}

public int getRate() {
return rate;
}

public void setRate(int rate) {
this.rate = rate;
}

public Date getToDate() {
return toDate;
}

public void setToDate(Date toDate) {
this.toDate = toDate;
}

public int getUnit() {
return unit;
}

public void setUnit(int unit) {
this.unit = unit;
}
}

can anyone help??? thanks!!!!