how to rectify these errors?

Line 20: Class BnCombo.BCombo of control cboSerType was not a loaded control class.
Line 338: Class BnCombo.BCombo of control cboClients was not a loaded control class.
Line 361: Class BnCombo.BCombo of control CboAttention was not a loaded control class.
Line 406: Class askComponents.CoolFlex of control cfx was not a loaded control class.
Line 415: Class BnCombo.BCombo of control CboMobRqd was not a loaded control class.
Line 438: Class BnCombo.BCombo of control CboPayTerm was not a loaded control class.