Conversion ERROR

This is the error message I get: :(
Server: Msg 242, Level 16, State 3, Line 1
The conversion of a char data type to a datetime data type resulted in an out-of-range datetime value.

This is the query:
Select Qual_ins.CompanyCode, Qual_ins.ParticipantCode, Qual_ins.Ins_Code, Qual_ins.Plan_Code,
dbo.PremiumRate(Qual_Ins.Crit,Qual_Ins.PQB_Spec,Pl an_Mas.Extend_Fee,
Qual_Ins.Adjpremium,Qual_Ins.Adjpremiumper,Qual_In s.Adjpremend,
GetDate(),Qual_Ins.Cover_Amt, Plan_Mas.CR_A, Plan_Mas.CR_B,
Plan_Mas.CR_C, Plan_Mas.CR_D, Plan_Mas.CR_E, Plan_Mas.CR_F,
Plan_Mas.CR_G, Plan_Mas.CR_H, Plan_Mas.CR_I, Plan_Mas.CR_J,
Plan_Mas.CR_K, Plan_Mas.CR_L, Plan_Mas.CR_M, Plan_Mas.CR_N,
Plan_Mas.CR_O) AS PremiumRate
FROM Qual_ins, Plan_Mas
WHERE Qual_Ins.CompanyCode = 'ACME'
AND Qual_ins.ParticipantCode = 4
AND Plan_Mas.CompanyCode = Qual_ins.CompanyCode
AND Plan_Mas.Ins_Code = Qual_ins.Ins_Code
AND Plan_Mas.Plan_Code = Qual_ins.Plan_Code
Order BY Qual_ins.Ins_Code

Please let me know if you need to see my PremiumRate (User Defined Function) in order to help me elimate this error message.
Any help is appreciate!
I'm new to this... "Hello" to all!

ShuviBased on the error message, I'd guess that you are trying to convert a string (CHAR or VARCHAR) to a DATETIME or a SMALLDATETIME. If that is the case, then one or more rows in your data isn't a valid date string.

-PatP